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