#include<iostream>
#include<string>
using namespace std;
int main(){
	int n;
	double a,b;
	cin>>n;
	cin>>a;
	b=a;
	for(int i=1;i<n;i++){
		cin>>a;
		b=b/(i+1)*i+a/(i+1);
	}
	int c=b;
	cout<<c<<endl;
    return 0;
}