#include<iostream>
using namsepace std;
class Statistics {
    float mean;
    public:
    Statistics()
    {
        int n;
        cin>>n;
        if (n<=0)
        {
            cout<<"Invalid input";
            mean=-1;
            return;
        }
        int num,sum=0;
        for int(int i=0;i<n;i++)
        {
            cin>>num;
            sum+=num;
        }
        mean=(float)sum/m;
        cout<<mean;
    }
    int main()
    {
        statistics obj;
        return 0;
    }