#include <bits/stdc++.h>
using namespace std;

int main() {
   string s1;
   cin >> s1;
   bool test[128] = {false};
   int tot=0;
   for(auto c : s1){
    if(!test[c]) tot++;
    test[c] = 1;
   }
   cout << tot <<endl;
   return 0;



}