#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string s) {
    int digit=0, lower=0, upper=0, special=0;
    for(int i=0;i<n;i++){
        if(s[i]>='0' && s[i]<='9')
            digit++;
        else if(s[i]>='a' && s[i]<='z')
            lower++;
        else if(s[i]>='A' && s[i]<='Z')
            upper++;
        else if(s[i]=='&' || s[i]=='$' || s[i]=='@' || s[i]=='!' || s[i]=='#' || s[i]=='%' || s[i]=='^' || s[i]=='*' || s[i]=='(' || s[i]==')' || s[i]=='-' || s[i]=='+')
            special++;
    }
    
    
    int sum=0;
    if(special>0)
        sum++;
    if(digit>0)
        sum++;
    if(lower>0)
        sum++;
    if(upper>0)
        sum++;
    
    
    if(n>=6 && sum==4)
        return 0;
    if(n>=6 && sum<4)
        return 4-sum;
    if(n<6 && sum==4)
        return 6-n;
    if(n<6 && sum<4){
        return max(6-n, 4-sum);
    }
    return 0;
    
    // Return the minimum number of characters to make the password strong
}

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