#include<iostream>
using namespace std;
class 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<<"Invaid input";
    else
    cout<<mean;
}
};
int main()
{
    int n;
    cin>>n;
    if(n<0)
    {
        cout<<"Invaid 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;
}