#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    string s;
    int n,p=4,a,b,c,d,i;
    a=b=c=d=0;
    cin>>n>>s;
    for(i=0;i<n;i++){
        if(!a&&s[i]>='A'&&s[i]<='Z'){
            a++;    p--;
        }
        else if(!b&&s[i]>='a'&&s[i]<='z'){
            b++;    p--; //   cout<<p<<endl;
        }
        else if(!c&&s[i]>='0'&&s[i]<='9'){
            c++;    p--;
        }
        else if(!d&&!((s[i]>='0'&&s[i]<='9')||(s[i]>='a'&&s[i]<='z')||(s[i]>='A'&&s[i]<='Z'))){
            d++;    p--;  //  cout<<p<<endl;
        }  // cout<<s[i]<<endl;
    }   //cout<<p<<endl;
    cout<<max(6-n,p);
    return 0;
}