#include <bits/stdc++.h>
#define ll long long int

using namespace std;

int arr[10];

int main(){

    //cout<<(int)'+'<<endl;

    int n;
    cin>>n;
    string s;
    cin>>s;

    if (n>=6){
        arr[0]=1;
    }

    for(int i=0;i<n;i++){
        if (s[i]>='0' && s[i]<='9'){
            arr[1]=1;
        }
        else if (s[i]>='a' && s[i]<='z'){
            arr[2]=1;
        }
        else if (s[i]>='A' && s[i]<='Z'){
            arr[3]=1;
        }
        else {
            arr[4]=1;
        }

    }


    int missing=0;

    for(int i=1;i<=4;i++){
        if (arr[i]==0)
            missing++;
    }

    int ans=max(missing,6-n);

    cout<<ans;


}