#include <bits/stdc++.h>
using namespace std;
void prepare() {}
void solve() {
  string s;
  cin >> s;
  set<int> ss[26];
  for (int i = 0; i < s.size(); ++i) ss[s[i] - 'a'].insert(i);
  int i = 25;
  int cur = -1;
  while (i != -1) {
    if (ss[i].empty()) {
      --i;
      continue;
    }
    while (!ss[i].empty() && *ss[i].begin() < cur) ss[i].erase(ss[i].begin());
    if (ss[i].empty()) {
      --i;
      continue;
    }
    for (int j = 0; j < ss[i].size(); ++j) printf("%c", i + 'a');
    cur = *(--ss[i].end());
    --i;
  }
}
int main() {
  prepare();
  solve();
  return 0;
}
