#include <bits/stdc++.h>
using namespace std;
int main() {
  char s[1000], s1[1000], z[1000];
  cin.getline(s, 1000);
  long int k = 0, i, j, c, ans = 0;
  for (i = 0; i < strlen(s); i++) {
    if (s[i] >= 97 && s[i] <= 122) {
      s1[k] = s[i];
      k++;
    }
  }
  z[0] = s1[0];
  long int p = 1;
  for (i = 1; i < k; i++) {
    for (j = 0; j < i; j++) {
      if (s1[i] == z[j]) break;
    }
    if (i == j) {
      z[p] = s1[i];
      p++;
    }
  }
  if (k == 0)
    cout << 0;
  else if (p == 24)
    cout << p + 2;
  else
    cout << p;
}
