#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 digit=0;
    int lc=0;
    int uc=0;
    int spcl=0;
    
    for(int i=0; i<n; i++)
    {
        if((int)password.at(i)>=48 && (int)password.at(i)<=57)
        {
            digit++;
        }
        if((int)password.at(i)>=97 && (int)password.at(i)<=122)
        {
            lc++;
        }
        if((int)password.at(i)>=65 && (int)password.at(i)<=90)
        {
            uc++;
        }
        if((int)password.at(i)>=33 && (int)password.at(i)<=45)
        {
            spcl++;
        }
    }
    
    int count=0;
    if(digit==0)
        count++;
    if(lc==0)
        count++;
    if(uc==0)
        count++;
    if(spcl==0)
        count++;
    
    if((n+count)>=6)
        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;
}