#include <bits/stdc++.h>
using namespace std;
int minimumNumber(int n, string pass)
{
    // Return the minimum number of characters to make the password strong
    int size = pass.size(), count = 0;
    bool d, u, l, s;
    d = u = l = s = false;
        for(int i = 0; i < size; i++)
        {
            if(isupper(pass[i]))
                u = true;
            else if(islower(pass[i]))
                l = true;
            else if(pass[i] >= '0' && pass[i] <= '9')
                d = true;
            else
                s = true;            
        }    
        if(!u)
            count++;
        if(!l)
            count++;
        if(!d)
            count++;
        if(!s)
            count++;
    if(size + count < 6)
        return 6 - size;
    return count;
}

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