/* |-_-| */
#include <bits/stdc++.h>
using namespace std;

typedef long long int ll;

int main() {
    if(fopen("input.txt", "r")) {
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    }
    
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    string numbers = "0123456789",
            lower_case = "abcdefghijklmnopqrstuvwxyz",
            upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
            special_characters = "!@#$%^&*()-+";

    int n;
    cin >> n;
    string s;
    cin >> s;
    int ans = 0;
    if(n < 6) {
        ans = 6-n;
    }

    int num, lower, upper, special;
    num = lower = upper = special = 0;

    for(int i = 0;i < n;i++) {
        if(numbers.find(s[i]) != string::npos) {
            num = 1;
        }
        else if(lower_case.find(s[i]) != string::npos) {
            lower = 1;
        }   
        else if(upper_case.find(s[i]) != string::npos) {
            upper = 1;
        }
        else if(special_characters.find(s[i]) != string::npos) {
            special = 1;
        }
    }

    int c = 4 - (num + lower + upper + special);
//    cout << num << lower << upper << special;
    ans = max(ans, c);

    cout << ans << endl;
    return 0;
}