#include<iostream>
#include<math.h>
#include<vector>
#include<algorithm>
#include<cstdio>
#include <string>
using namespace std;
 
int main(){
   int n,i;
   long long tmp,sum=0;
   long mean;
   cin>>n;
   for(i=0;i<n;i++){
       cin>>tmp;
        sum+=tmp;
   }
   mean=sum/6;
   cout<<mean<<endl;
    return 0;
}
