#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;
    }
    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<)
    {
        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;
}