#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<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;
    
}