#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    int i,flLow=1,flUp=1,flSp=1,flDig=1;
    for(i=0;i<n;i++){
        if(password[i]>=97 && password[i]<=122) flLow = 0;
        else if(password[i]>=65 && password[i]<=90) flUp = 0;
        else if((password[i]>=33 && password[i]<=45) || password[i]=='@') flSp = 0;
        else if(password[i]>=48 && password[i]<=57) flDig = 0;
    }
    int minNum=0,minRes=0;
    if(6>n) minNum = 6-n;
    minRes = flLow + flUp + flSp + flDig;
    if(minRes>minNum) return minRes;
    else return minNum;
}

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