#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    int a=0, b=0, c=0, d=0;
    for(int i=0; i<n; i++)
    {
        if(password[i]>47 && password[i]<58)
        {
            a++;
        }
        else if(password[i]>64 && password[i]<91)
            b++;
        else if(password[i]>96 && password[i]<123)
            c++;
        else if(password[i]==33 || password[i]==35 || password[i]==36 || password[i]==37||password[i]==38||password[i]==94||password[i]==40 ||password[i]==41||password[i]==42||password[i]==43||password[i]==45||password[i]==64)
        {
            d++;
        }
    }
    int x=4;
 
    if(a>0)
        x--;
    if(b>0)
        x--;
    if(d>0)
        x--;
    if(c>0)
        x--;
    int y=6-n;
    if(y<=0)
    {
        return x;
    }
    else if(y>x)
        return y;
    else
        return x;
}

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