#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int number, string password) {
    int valid[] = {0,0,0,0};
    for(int i = 0; i < number; ++i) {
        char c = password[i];
        if( c >= 48 && c <= 57) {
            ++valid[0];
        } else if( c >= 97 && c <= 122) {
            ++valid[1];
        } else if( c>= 65 && c <= 90) {
            ++valid[2];
        } else {
            ++valid[3];
        }
    }

    int result = 0;
    for (int j : valid) {
        if(j == 0)
            ++result;
    }
        if( number + result < 6) {
        result += 6- (number+result);
    }
    return result;
}

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