#include <bits/stdc++.h>
using namespace std;
int i;
char x[100005];
long long y;
int main() {
  scanf("%s", x);
  while (x[i]) {
    if (x[i] >= 'a' && x[i] <= 'z')
      y += ((long long)x[i] - 'a' + 1) * 0 - ((long long)x[i] - 'a' + 1) * 1;
    else if (x[i] >= 'A' && x[i] <= 'Z')
      y += ((long long)x[i] - 'A' + 1) * 1 - ((long long)x[i] - 'A' + 1) * 0;
    i++;
  }
  printf("%I64d\n", y);
  return 0;
}
