#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string s) {
    // Return the minimum number of characters to make the password strong
    int cnt1=0,cnt2=0,cnt3=0,cnt4=0;
    for(int i=0;i<n;i++){
        if(s[i]>=48 && s[i]<=57){
            cnt1=1;
        }
        else if(s[i]>=65 && s[i]<=90){
            cnt2=1;
        }
        else if(s[i]>=97 && s[i]<=122){
            cnt3=1;
        }
        else if(s[i]==33 ||s[i]==64|| s[i]==35|| s[i]==36|| s[i]==37|| s[i]==38|| s[i]==42|| s[i]==43|| s[i]==45|| s[i]==94|| s[i]==40|| s[i]==41){
            cnt4=1;
        }
    }
    int ans2=0;
    int ans=4-cnt1-cnt2-cnt3-cnt4;
    if(s.length()<6)
    ans2=6-s.length();
    if(ans2>ans)
        return ans2;
    else
        return ans;
    
}

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