#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    int digit = 0;
    int special = 0;
    int lower = 0;
    int upper = 0;
    for (int i = 0; i < n; i++) {
        char c = password[i];
        if (c <= '9' && c >= '0') {
            digit = 1;
        } else if (c <= 'z' && c >= 'a') {
            lower = 1;
        } else if (c <= 'Z' && c >= 'A') {
            upper = 1;
        } else {
            special = 1;
        }
    }
    int need = max(6 - n, 4 - digit - special - lower - upper);
    return max(need, 0);
}

int main() {
    int n;
    cin >> n;
    string password;
    cin >> password;
    int answer = minimumNumber(n, password);
    cout << answer << endl;
    return 0;
}