#include <bits/stdc++.h>
using namespace std;
string s;
int main() {
  int count = 0;
  getline(cin, s);
  for (int i = 1; i < s.length() - 1; i = i + 3) {
    int j = 1;
    for (j; j < i; j += 3) {
      if (s[j] == s[i]) break;
    }
    if (j == i) count++;
  }
  cout << count;
  return 0;
}
