#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string p) {
    int l=0,u=0,s=0,d=0,ans=0;
    for(int i=0;i<n;i++){
        if(p[i]>64 && p[i]<91) u++;
        else if(p[i]>96 && p[i]<123) l++;
        else if(p[i]>47 && p[i]<58) d++;
        else s++;
    }
       if(l==0) ans++; 
       if(d==0) ans++;
       if(u==0) ans++;
       if(s==0) ans++;
       if(n+ans<6) ans+=6-n-ans;
       return ans;
}

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