#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    int min = 4;
    string numbers = "0123456789";
    string lower_case = "abcdefghijklmnopqrstuvwxyz";
    string upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    string special_characters = "!@#$%^&*()-+";
    bool num = false,low = false, up = false,spec = false;
    for(int i = 0; i< n; i++){
        if (numbers.find(password[i]) != std::string::npos && !num){
            num=true;
            min--;
        }else if(lower_case.find(password[i]) != std::string::npos && !low){
            low = true;
            min--;
        }else if(upper_case.find(password[i]) != std::string::npos && !up){    
            up=true;
            min--;
        }else if(special_characters.find(password[i]) != std::string::npos && !spec){
            spec = true;
            min--;
        }
    }
    if(min < 6 - n){
        min = 6-n;
    }
    return min;
}

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