unordered_map<char,int>

#include <iostream>
#include <string>
#include <unordered_map>
using namespace std;

int main() {
    char c;
    unordered_map<char, int> mp;
    while (cin >> c) {
        mp[c]++;
    }
    cout << mp.size() << endl;
    return 0;
}