// editor1
#include<iostream>
#include<string>
using namespace std;
int main()
{
    int n;
    cin>>n;
    try {
        if (n<1 || n>10)
        {
            throw "Invalid input";
        }
        double grade;
        duble 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* msg){
        cout << msg;
    }
    return 0;
}