#include <bits/stdc++.h>
using namespace std;
int convert(char c) {
  if (c >= 'A' && c <= 'Z')
    return c - 64;
  else if (c >= 'a' && c <= 'z')
    return c - 96;
  else
    return 0;
}
int main() {
  string str;
  int res = 0;
  cin >> str;
  for (int i = 0; i < str.length(); i++) {
    res += convert(str[i]) *
           ((str[i] > '@' && str[i] < '[') - (str[i] > '`' && str[i] < '{'));
  }
  cout << res << endl;
  return 0;
}
