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

int main() {
    string s;
    getline(cin, s);
    int arr[500] = {}, res = 0;
    for (int i = 0; i < s.length(); i++) {
        if (s[i] >= 'a' && s[i] <= 'z') {
            s[i] -= 'a' - 'A';
        }
        if (arr[s[i]] == 0) {
            arr[s[i]] = 1;
            res++;
        }
    }
    cout << res;
}