#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(int i=0;i<n;i++)
    {
        sum+=arr[i]
    }
    mean=(float)sum/n;
    }
    static(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;
}