#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    int length=password.size();int a=0,b=0,c=0,d=0;int temp=0;
    for(int i=0;i<length;i++){
        if(password.at(i)>=97 && password.at(i)<=122)a=1;
        else if(password.at(i)>=48 && password.at(i)<=57)b=1;
        else if(password.at(i)>=65 && password.at(i)<=90)c=1;
        else {if(password.at(i)=='!' || password.at(i)=='@' || password.at(i)=='#' || password.at(i)=='$' || password.at(i)=='%' || password.at(i)=='^' || password.at(i)=='&' || password.at(i)=='*' || password.at(i)=='()' || password.at(i)=='-' || password.at(i)=='+')d=1;
             }
        if(a!=0 && b!=0 && c!=0 && d!=0){temp++;break;}
    }
    int ch=max((6-length),(4-a-b-c-d));
    return ch;
    // Return the minimum number of characters to make the password strong
}

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