#include<iostream>
using namespace std;
 class statistics{
     float mean;
public:
    statistics(int arr[],int n){
        if (n<=0){
            mean=-1;
            return;
        }
        int sum = 0;
        for (inti=0;i<n;i++){
            sum += arr[i];
        }
        mean=(float)sum/n;
    }
    statistics(const statistics &obj){
        mean=obj.mean;
    }
    void display(){
        if (mean==-1)
           cout<<"Invalid input";
         else
            cout<<mean;
    }
 };
 int main(){
     int n;
     cin >> n;
     
     if(n<0){
         cout<<"Invalid input";
         return 0;
     }
     int arr[100];
     
     for (int i=0;i<n;i++){
         cin>>arr[i];
         
     }
     statistics s1(arr, n);
     statistics s2 = s1;
     
     s2.display();
     
     return 0;
 }