#include <bits/stdc++.h>
using namespace std;

void minimumNumber(int n, string s) {
    bool lo = true, up = true, d = true, spec = true;
    int cnt = 0;
    for(int i = 0; i < n; i++) {
        if(s[i] >= 'a' && s[i] <= 'z' && lo) {
            lo = false;
            cnt++;
        } else if(s[i] >= 'A' && s[i] <= 'Z' && up) {
            up = false;
            cnt++;
        } else if(isdigit(s[i]) && d) {
            d = false;
            cnt++;
        } else if((s[i] == '!' || s[i] == '@' || s[i] == '#' || s[i] == '$' || s[i] == '%' || s[i] == '^' || s[i] == '&'
                 || s[i] == '*' || s[i] == '(' || s[i] == ')' || s[i] == '-' || s[i] == '+') && spec) {
            spec = false;
            cnt++;
        }
    }
    
    if(cnt == 4 && n >= 6) {
        cout << 0 << endl;
    } else if(cnt == 4 && n < 6) {
        cout << 6 - n << endl;
    } else if(cnt != 4 && n >= 6){
        cout << 4 - cnt << endl;
    } else if(cnt != 4 && n < 6) {
        if((4 - cnt) + n >= 6) {
            cout << 4 - cnt << endl;
        } else {
            cout << 6 - n << endl;
        }
    }
}

int main() {
    int n;
    cin >> n;
    string password;
    cin >> password;
    minimumNumber(n, password);
    return 0;
}