#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    // Return the minimum number of characters to make the password strong
    int lenFlag, lowerFlag, upperFlag, numFlag, specialFlag;
    lenFlag=lowerFlag=upperFlag=numFlag=specialFlag=1;
    for(int i=0;i<n;i++)
    {
        if(password[i]>='0' && password[i]<='9')
            numFlag=0;
        else if(password[i]>='a' && password[i]<='z')
            lowerFlag=0;
        else if(password[i]>='A' && password[i]<='Z')
            upperFlag=0;
        else
            specialFlag=0;
    }
    int count = numFlag+lowerFlag+upperFlag+specialFlag;
    if(n>=6)
        return count;
    else
    {
        if(6-n <= count)
            return count;
        else
            return 6-n;
    }
}

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