#include <bits/stdc++.h>

using namespace std;

int n, a, b, c, d;
string s;

int main() {
    cin >> n >> s;
    for (int i = 0; i < n; i++) {
        if (s[i] >= '0' && s[i] <= '9') a = 1;
        else if (s[i] >= 'a' && s[i] <= 'z') b = 1;
        else if (s[i] >= 'A' && s[i] <= 'Z') c = 1;
        else d = 1;
    }
    cout << max(6 - n, 4 - a - b - c - d);
    return 0;
}