#include <iostream>
using namespace std;
{
    int n;
    cin>>n;
    try{
        if(n<1||n>10)
        {
            throw"Invalid input";
        }
        double grade;
        double 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;
}