#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string p) {
    string numbers = "0123456789";
    string lower_case = "abcdefghijklmnopqrstuvwxyz";
    string upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    string special_characters = "!@#$%^&*()-+";
    
    
    vector<int> check(4,0);
    
    for(int i=0;i<n;i++)
    {
        if(numbers.find(p[i])!=string::npos)
            check[0]=1;
        else if(lower_case.find(p[i])!=string::npos)
            check[1]=1;
        else if(upper_case.find(p[i])!=string::npos)
            check[2]=1;
        else if(special_characters.find(p[i])!=string::npos)
            check[3]=1;
    }
    int sum=0;
    for(int i=0;i<4;i++)
    {
        sum+=check[i];
    }
    sum=4-sum;
    if(n>=6)
    {
        return sum;
    }
    else
    {
        return ((6-n)>sum)?6-n:sum;
    }
    // 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;
}