#include <bits/stdc++.h>

using namespace std;


int minimumNumber(int n, string password) {
    int count=0;
    int x1=0,x2=0,x3=0,x4=0;
    for(int i=0;i<n;i++)
    {
        if( password[i]-'a'>=0 &&  password[i]-'a'<26 && x1==0 ){
            count++;
            x1=1;
        }
        if( password[i]-'A'>=0 &&  password[i]-'A'<26 && x2==0){
            count++;
            x2=1;
        }
        if( password[i]-'0'>=0 &&  password[i]-'0'<10 && x3==0){
            count++;
            x3=1;
        }
            if((password[i]=='!' || password[i]=='@' || password[i]=='#' || password[i]=='$'|| password[i]=='%' || password[i]=='^' || password[i]=='&'|| password[i]=='*' || password[i]=='(' || password[i]==')' ||password[i]=='+'||password[i]=='-') && x4==0)
            {
                count++;
                x4=1;
            }
    }
    if(count==4 && n>=6)
        return 0;
    if(count==4 && n<6)
        return 6-n;
    if(count<4 && n>=6)
        return 4-count;
    if(count<4 && n<6){
        int add=4-count;
        if(n+add<6)
            return 6-n;
        else
            return add;
    }
    return 0;
        
}

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