#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<<gpa;
    }
    return 0;
}