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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */  
    int n;
    cin>>n;
    string s;
    cin>>s;
    int cA=0,ca=0,cs=0,cd=0;
    for(int i=0;i<n;i++){
        if(isupper(s[i])){
            cA=1;
        }
       else if(islower(s[i])){
           ca=1;
       }
        else if(isdigit(s[i])){
            cd=1;
        }
        else{
            cs=1;
        }
    }
    if(ca==1&&cA==1&&cs==1&&cd==1&&n>=6){
        cout<<0;
    }
    int z=ca+cA+cs+cd;
    if(z!=4){
        if(n>=6){
           cout<<4-z;
        }
        if(n<6){
            if((4-z+n)>6){
                cout<<4-z;
            }
            else{
                int x=4-z;
                int k=n+4-z;
                int m=6-k;
                cout<<m+x;
            }
        }
    }
    if(z==4&&n<6){
        cout<<6-n;
    }
        
    return 0;
}