#include <bits/stdc++.h>
using namespace std;
string str[] = {"4",         "7",         "44",        "47",        "74",
                "77",        "444",       "447",       "474",       "477",
                "744",       "747",       "774",       "777",       "4444",
                "4447",      "4474",      "4477",      "4744",      "4747",
                "4774",      "4777",      "7444",      "7447",      "7474",
                "7477",      "7744",      "7747",      "7774",      "7777",
                "44444",     "44447",     "44474",     "44477",     "44744",
                "44747",     "44774",     "44777",     "47444",     "47447",
                "47474",     "47477",     "47744",     "47747",     "47774",
                "47777",     "74444",     "74447",     "74474",     "74477",
                "74744",     "74747",     "74774",     "74777",     "77444",
                "77447",     "77474",     "77477",     "77744",     "77747",
                "77774",     "77777",     "444444",    "444447",    "444474",
                "444477",    "444744",    "444747",    "444774",    "444777",
                "447444",    "447447",    "447474",    "447477",    "447744",
                "447747",    "447774",    "447777",    "474444",    "474447",
                "474474",    "474477",    "474744",    "474747",    "474774",
                "474777",    "477444",    "477447",    "477474",    "477477",
                "477744",    "477747",    "477774",    "477777",    "744444",
                "744447",    "744474",    "744477",    "744744",    "744747",
                "744774",    "744777",    "747444",    "747447",    "747474",
                "747477",    "747744",    "747747",    "747774",    "747777",
                "774444",    "774447",    "774474",    "774477",    "774744",
                "774747",    "774774",    "774777",    "777444",    "777447",
                "777474",    "777477",    "777744",    "777747",    "777774",
                "777777",    "4444444",   "4444447",   "4444474",   "4444477",
                "4444744",   "4444747",   "4444774",   "4444777",   "4447444",
                "4447447",   "4447474",   "4447477",   "4447744",   "4447747",
                "4447774",   "4447777",   "4474444",   "4474447",   "4474474",
                "4474477",   "4474744",   "4474747",   "4474774",   "4474777",
                "4477444",   "4477447",   "4477474",   "4477477",   "4477744",
                "4477747",   "4477774",   "4477777",   "4744444",   "4744447",
                "4744474",   "4744477",   "4744744",   "4744747",   "4744774",
                "4744777",   "4747444",   "4747447",   "4747474",   "4747477",
                "4747744",   "4747747",   "4747774",   "4747777",   "4774444",
                "4774447",   "4774474",   "4774477",   "4774744",   "4774747",
                "4774774",   "4774777",   "4777444",   "4777447",   "4777474",
                "4777477",   "4777744",   "4777747",   "4777774",   "4777777",
                "7444444",   "7444447",   "7444474",   "7444477",   "7444744",
                "7444747",   "7444774",   "7444777",   "7447444",   "7447447",
                "7447474",   "7447477",   "7447744",   "7447747",   "7447774",
                "7447777",   "7474444",   "7474447",   "7474474",   "7474477",
                "7474744",   "7474747",   "7474774",   "7474777",   "7477444",
                "7477447",   "7477474",   "7477477",   "7477744",   "7477747",
                "7477774",   "7477777",   "7744444",   "7744447",   "7744474",
                "7744477",   "7744744",   "7744747",   "7744774",   "7744777",
                "7747444",   "7747447",   "7747474",   "7747477",   "7747744",
                "7747747",   "7747774",   "7747777",   "7774444",   "7774447",
                "7774474",   "7774477",   "7774744",   "7774747",   "7774774",
                "7774777",   "7777444",   "7777447",   "7777474",   "7777477",
                "7777744",   "7777747",   "7777774",   "7777777",   "44444444",
                "44444447",  "44444474",  "44444477",  "44444744",  "44444747",
                "44444774",  "44444777",  "44447444",  "44447447",  "44447474",
                "44447477",  "44447744",  "44447747",  "44447774",  "44447777",
                "44474444",  "44474447",  "44474474",  "44474477",  "44474744",
                "44474747",  "44474774",  "44474777",  "44477444",  "44477447",
                "44477474",  "44477477",  "44477744",  "44477747",  "44477774",
                "44477777",  "44744444",  "44744447",  "44744474",  "44744477",
                "44744744",  "44744747",  "44744774",  "44744777",  "44747444",
                "44747447",  "44747474",  "44747477",  "44747744",  "44747747",
                "44747774",  "44747777",  "44774444",  "44774447",  "44774474",
                "44774477",  "44774744",  "44774747",  "44774774",  "44774777",
                "44777444",  "44777447",  "44777474",  "44777477",  "44777744",
                "44777747",  "44777774",  "44777777",  "47444444",  "47444447",
                "47444474",  "47444477",  "47444744",  "47444747",  "47444774",
                "47444777",  "47447444",  "47447447",  "47447474",  "47447477",
                "47447744",  "47447747",  "47447774",  "47447777",  "47474444",
                "47474447",  "47474474",  "47474477",  "47474744",  "47474747",
                "47474774",  "47474777",  "47477444",  "47477447",  "47477474",
                "47477477",  "47477744",  "47477747",  "47477774",  "47477777",
                "47744444",  "47744447",  "47744474",  "47744477",  "47744744",
                "47744747",  "47744774",  "47744777",  "47747444",  "47747447",
                "47747474",  "47747477",  "47747744",  "47747747",  "47747774",
                "47747777",  "47774444",  "47774447",  "47774474",  "47774477",
                "47774744",  "47774747",  "47774774",  "47774777",  "47777444",
                "47777447",  "47777474",  "47777477",  "47777744",  "47777747",
                "47777774",  "47777777",  "74444444",  "74444447",  "74444474",
                "74444477",  "74444744",  "74444747",  "74444774",  "74444777",
                "74447444",  "74447447",  "74447474",  "74447477",  "74447744",
                "74447747",  "74447774",  "74447777",  "74474444",  "74474447",
                "74474474",  "74474477",  "74474744",  "74474747",  "74474774",
                "74474777",  "74477444",  "74477447",  "74477474",  "74477477",
                "74477744",  "74477747",  "74477774",  "74477777",  "74744444",
                "74744447",  "74744474",  "74744477",  "74744744",  "74744747",
                "74744774",  "74744777",  "74747444",  "74747447",  "74747474",
                "74747477",  "74747744",  "74747747",  "74747774",  "74747777",
                "74774444",  "74774447",  "74774474",  "74774477",  "74774744",
                "74774747",  "74774774",  "74774777",  "74777444",  "74777447",
                "74777474",  "74777477",  "74777744",  "74777747",  "74777774",
                "74777777",  "77444444",  "77444447",  "77444474",  "77444477",
                "77444744",  "77444747",  "77444774",  "77444777",  "77447444",
                "77447447",  "77447474",  "77447477",  "77447744",  "77447747",
                "77447774",  "77447777",  "77474444",  "77474447",  "77474474",
                "77474477",  "77474744",  "77474747",  "77474774",  "77474777",
                "77477444",  "77477447",  "77477474",  "77477477",  "77477744",
                "77477747",  "77477774",  "77477777",  "77744444",  "77744447",
                "77744474",  "77744477",  "77744744",  "77744747",  "77744774",
                "77744777",  "77747444",  "77747447",  "77747474",  "77747477",
                "77747744",  "77747747",  "77747774",  "77747777",  "77774444",
                "77774447",  "77774474",  "77774477",  "77774744",  "77774747",
                "77774774",  "77774777",  "77777444",  "77777447",  "77777474",
                "77777477",  "77777744",  "77777747",  "77777774",  "77777777",
                "444444444", "444444447", "444444474", "444444477", "444444744",
                "444444747", "444444774", "444444777", "444447444", "444447447",
                "444447474", "444447477", "444447744", "444447747", "444447774",
                "444447777", "444474444", "444474447", "444474474", "444474477",
                "444474744", "444474747", "444474774", "444474777", "444477444",
                "444477447", "444477474", "444477477", "444477744", "444477747",
                "444477774", "444477777", "444744444", "444744447", "444744474",
                "444744477", "444744744", "444744747", "444744774", "444744777",
                "444747444", "444747447", "444747474", "444747477", "444747744",
                "444747747", "444747774", "444747777", "444774444", "444774447",
                "444774474", "444774477", "444774744", "444774747", "444774774",
                "444774777", "444777444", "444777447", "444777474", "444777477",
                "444777744", "444777747", "444777774", "444777777", "447444444",
                "447444447", "447444474", "447444477", "447444744", "447444747",
                "447444774", "447444777", "447447444", "447447447", "447447474",
                "447447477", "447447744", "447447747", "447447774", "447447777",
                "447474444", "447474447", "447474474", "447474477", "447474744",
                "447474747", "447474774", "447474777", "447477444", "447477447",
                "447477474", "447477477", "447477744", "447477747", "447477774",
                "447477777", "447744444", "447744447", "447744474", "447744477",
                "447744744", "447744747", "447744774", "447744777", "447747444",
                "447747447", "447747474", "447747477", "447747744", "447747747",
                "447747774", "447747777", "447774444", "447774447", "447774474",
                "447774477", "447774744", "447774747", "447774774", "447774777",
                "447777444", "447777447", "447777474", "447777477", "447777744",
                "447777747", "447777774", "447777777", "474444444", "474444447",
                "474444474", "474444477", "474444744", "474444747", "474444774",
                "474444777", "474447444", "474447447", "474447474", "474447477",
                "474447744", "474447747", "474447774", "474447777", "474474444",
                "474474447", "474474474", "474474477", "474474744", "474474747",
                "474474774", "474474777", "474477444", "474477447", "474477474",
                "474477477", "474477744", "474477747", "474477774", "474477777",
                "474744444", "474744447", "474744474", "474744477", "474744744",
                "474744747", "474744774", "474744777", "474747444", "474747447",
                "474747474", "474747477", "474747744", "474747747", "474747774",
                "474747777", "474774444", "474774447", "474774474", "474774477",
                "474774744", "474774747", "474774774", "474774777", "474777444",
                "474777447", "474777474", "474777477", "474777744", "474777747",
                "474777774", "474777777", "477444444", "477444447", "477444474",
                "477444477", "477444744", "477444747", "477444774", "477444777",
                "477447444", "477447447", "477447474", "477447477", "477447744",
                "477447747", "477447774", "477447777", "477474444", "477474447",
                "477474474", "477474477", "477474744", "477474747", "477474774",
                "477474777", "477477444", "477477447", "477477474", "477477477",
                "477477744", "477477747", "477477774", "477477777", "477744444",
                "477744447", "477744474", "477744477", "477744744", "477744747",
                "477744774", "477744777", "477747444", "477747447", "477747474",
                "477747477", "477747744", "477747747", "477747774", "477747777",
                "477774444", "477774447", "477774474", "477774477", "477774744",
                "477774747", "477774774", "477774777", "477777444", "477777447",
                "477777474", "477777477", "477777744", "477777747", "477777774",
                "477777777", "744444444", "744444447", "744444474", "744444477",
                "744444744", "744444747", "744444774", "744444777", "744447444",
                "744447447", "744447474", "744447477", "744447744", "744447747",
                "744447774", "744447777", "744474444", "744474447", "744474474",
                "744474477", "744474744", "744474747", "744474774", "744474777",
                "744477444", "744477447", "744477474", "744477477", "744477744",
                "744477747", "744477774", "744477777", "744744444", "744744447",
                "744744474", "744744477", "744744744", "744744747", "744744774",
                "744744777", "744747444", "744747447", "744747474", "744747477",
                "744747744", "744747747", "744747774", "744747777", "744774444",
                "744774447", "744774474", "744774477", "744774744", "744774747",
                "744774774", "744774777", "744777444", "744777447", "744777474",
                "744777477", "744777744", "744777747", "744777774", "744777777",
                "747444444", "747444447", "747444474", "747444477", "747444744",
                "747444747", "747444774", "747444777", "747447444", "747447447",
                "747447474", "747447477", "747447744", "747447747", "747447774",
                "747447777", "747474444", "747474447", "747474474", "747474477",
                "747474744", "747474747", "747474774", "747474777", "747477444",
                "747477447", "747477474", "747477477", "747477744", "747477747",
                "747477774", "747477777", "747744444", "747744447", "747744474",
                "747744477", "747744744", "747744747", "747744774", "747744777",
                "747747444", "747747447", "747747474", "747747477", "747747744",
                "747747747", "747747774", "747747777", "747774444", "747774447",
                "747774474", "747774477", "747774744", "747774747", "747774774",
                "747774777", "747777444", "747777447", "747777474", "747777477",
                "747777744", "747777747", "747777774", "747777777", "774444444",
                "774444447", "774444474", "774444477", "774444744", "774444747",
                "774444774", "774444777", "774447444", "774447447", "774447474",
                "774447477", "774447744", "774447747", "774447774", "774447777",
                "774474444", "774474447", "774474474", "774474477", "774474744",
                "774474747", "774474774", "774474777", "774477444", "774477447",
                "774477474", "774477477", "774477744", "774477747", "774477774",
                "774477777", "774744444", "774744447", "774744474", "774744477",
                "774744744", "774744747", "774744774", "774744777", "774747444",
                "774747447", "774747474", "774747477", "774747744", "774747747",
                "774747774", "774747777", "774774444", "774774447", "774774474",
                "774774477", "774774744", "774774747", "774774774", "774774777",
                "774777444", "774777447", "774777474", "774777477", "774777744",
                "774777747", "774777774", "774777777", "777444444", "777444447",
                "777444474", "777444477", "777444744", "777444747", "777444774",
                "777444777", "777447444", "777447447", "777447474", "777447477",
                "777447744", "777447747", "777447774", "777447777", "777474444",
                "777474447", "777474474", "777474477", "777474744", "777474747",
                "777474774", "777474777", "777477444", "777477447", "777477474",
                "777477477", "777477744", "777477747", "777477774", "777477777",
                "777744444", "777744447", "777744474", "777744477", "777744744",
                "777744747", "777744774", "777744777", "777747444", "777747447",
                "777747474", "777747477", "777747744", "777747747", "777747774",
                "777747777", "777774444", "777774447", "777774474", "777774477",
                "777774744", "777774747", "777774774", "777774777", "777777444",
                "777777447", "777777474", "777777477", "777777744", "777777747",
                "777777774", "777777777"};
int main() {
  string num;
  cin >> num;
  for (int i = 0; i < 1022; i++) {
    if (num == str[i]) {
      printf("%d\n", i + 1);
      break;
    }
  }
  return 0;
}
