#include <bits/stdc++.h>
using namespace std;
unordered_set<char> s;//无序且无重复
char c;
int main(){
    while (cin>>c) {
        if(s.find(c)!=s.end()){
            continue;
        }
        s.insert(c);
    }
    cout<<s.size();
    return 0;
}