#include<iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    try{
        if(n < 1 || n > 10){
            throw"Invalid input"
        }
        
          double grade , sum = 0;
         for(int i=0;i<n;i++){
        cin>> grade;
        if(grade<0){
            throw<<"Invalid input"
        
        }
        sum =+ grade;
    }
    double gpa=sum/n;
    cout << gpa;
    }
    catch(const char * a){
    cout<<a;
}
    return 0;
}