#include<iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    double sum =0;
    int grade;
    for(int i = 0; i<n; i++){
        cin>>grade;
        if(grade<0){
            cout<<"Invalid input";
            return 0;
        }
        sum += grade;
    }
    doublegpa=sum/n;
    cout<<gpa;
    return 0;
}