#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    // Return the minimum number of characters to make the password strong
    vector<bool> A(4,false);
    for(int i=0;i<n;++i){
      if(password[i]>=48 && password[i]<=57) A[0]= true;
       else if(password[i]>=65 && password[i]<=90) A[1]=true;
        else if(password[i]>=97 && password[i]<=122) A[2]=true;
        else if(password[i] == 33 || (password[i]>=35 && password[i] <=38) || (password[i]>=40 && password[i] <=43) || password[i] == 94 
                || password[i] == 45 || password[i] == 64) A[3] = true;
    }
       int c = 0;
    
        for(int i=0;i<4;++i)
            if(!A[i]) ++c;
           // cout<<A[i]<<" ";}
        
    if(n>=6)
    return c;
    return max(c,6-n);
    
}

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