#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
using namespace std;

//string numbers ,lower_case,upper_case,special_characters;
string numbers = "0123456789";
string lower_case = "abcdefghijklmnopqrstuvwxyz";
string upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
string special_characters = "!@#$%^&*()-+";
int minimumNumber(int n, string password) {
    int a[4] = {0,0,0,0};
    for(int i=0;i<n;i++){
        if(numbers.find(password[i]) != numbers.npos)
            a[0] = 1;
         if(lower_case.find(password[i]) != lower_case.npos)
            a[1] = 1;
         if(upper_case.find(password[i]) != upper_case.npos)
            a[2] = 1;
         if(special_characters.find(password[i]) != special_characters.npos)
            a[3] = 1;
    }
    int count = 4-(a[0]+a[1]+a[2]+a[3]);
    int t=0;
    if(n < 6)
        t = 6 - n; 
    if(count < t)
        return t;
    else
        return count;
} 


int main() {
    int n;
    cin >> n;
    string s;
    cin >> s;
    cout << minimumNumber(n, s);
    return 0;
}