#include <iostream>

using namespace std;

int N, db;
string s;
bool a, b, c, d;

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