#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    int l=0,u=0,s=0,d=0;
    for(int i=0;i<n;i++){
        if(password[i]>=48&&password[i]<=57)
            d=1;
        else if(password[i]>=65 && password[i]<=90)
            u=1;
        else if(password[i]>=97 && password[i]<=122)
            l=1;
        else
            s=1;
    }
    int ans=0;
    if(d == 0)
       ans++;
    if(u == 0)
       ans++;
    if(l == 0)
       ans++;
    if(s == 0)
       ans++;
    if((ans+n) < 6)
        return 6-n;
    else
        return ans;
}

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