#include<iostream>
using namespace std;
int main(){
    int n;
    cin>>n;
    if(n<=0){
        cout<<"Invalid input";
        return 0;
    }
    double grade,sum=0;
    for(int i=0;i<n;i++){
        cin>>grade;
        if(grade<0)}
           cout<<"Invalid input";
           return 0;
    }
        sum+=grade;
    }
    double gpa=sum/n;
    cout<<gpa;
    return 0;
  
}