#include <bits/stdc++.h>

using namespace std;
int a,b,c,d;
int minimumNumber(int n, string password) {
for(int i=0;i<n;i++)
{
    int temp=password[i];
    if(temp>=97 && temp<=122)
        a++;
    if(temp>=65 && temp<=90)
        b++;
    if(temp>=48 && temp<=57)
        c++;
    if(temp==33 ||temp==34||temp==35||temp==36||temp==37||temp==64||temp==94||temp==42||temp==38||temp==40||temp==41||temp==43||temp==45)
        d++;
    
}
    if(n>=6 && a>0&&b>0&&c>0&&d>0)
        return 0;
    int e=0;
    if(a==0)
        e++;
    if(b==0)
        e++;
    if(c==0)
        e++;
    if(d==0)
        e++;
    if(n<6)
    {
        if(e+n<=6)
            return 6-n;
        return e;
    }
    return e;
       }

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