#include<iostream>
using namespace std;

class Statistics{
    private:
    double mean;
    public:
    Statistics(int arr[],int n){
        if(n <= 0){
            mean = -1;
            return;
        }
        int sum = 0;
        fot(int i = 0; i<n; i++){
            sum +=arr[i];
        }
        mean=(double)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[n];
    for(int i=0;i<n;i++){
        cin>>arr[i];
    }
    Statistics obj1(arr,n);
    Statistics obj2=obj1;
    
    obj2.display();
    return 0;
}