#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    vector<bool> cond(4,false);
    for(int i =0; i<n; i++)
    {
        if('a'<=password[i] && password[i]<='z')
        {
            cond[0]=true;
            continue;
        }
        if('A'<=password[i] && password[i]<='Z')
        {
            cond[1]=true;
            continue;
        }
        if('0'<=password[i] && password[i]<='9')
        {
            cond[2] =true; 
            continue;
        }
        cond[3] =true;
    }
    
    int res=0; 
    for(int i=0; i<4; i++)
    {
        if(cond[i] ==false)
            res++;
    }
    if((res+n)>=6)
        return res;
    else
        return (6-n);
        
    
}

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