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

int main() {
    string s;
    cin >> s;

    int cnt = 0;
    for(char c : s) {
        if(('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z'))
            cnt++;
    }

    cout << cnt << '\n';
    return 0;
}