#include <bits/stdc++.h>

using namespace std;
string str="!@#$%^&*()-+";
bool is_digit(char a){
    if(a>='0'&&a<='9')return true;
    return false;
}
bool is_lower(char a){
    if(a>='a'&&a<='z')return true;
    return false;
}
bool is_upper(char a){
    if(a>='A'&&a<='Z')return true;
    return false;
}
bool is_spe(char a){
    for(int i=0;i<str.length();i++)
        if(str[i]==a)return true;
    
    return true;
}
int minimumNumber(int n, string password) {
    
    bool digit=false,lower=false,upper=false,special=false;
   // int n=password.length();
    for(int i=0;i<n;i++){
        if(is_digit(password[i]))digit=true;
        else if(is_lower(password[i]))lower=true;
        else if(is_upper(password[i]))upper=true;
        else if(is_spe(password[i]))special=true;
    }
    int count=0;
    if(!digit)count++;
    if(!lower)count++;
    if(!upper)count++;
    if(!special)count++;
    
    return max(count,6-n);
            
        

}

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