#include<iostream>
using namespace std;
int main()
{
	int x,s,n;
	float m;
	s=0; n=0;
	cout<<"x="; cin>>x;
	while(x!=0)
	{
		s=s+x;
		n++;
		cout<<"x="; cin>>x;
	}
	m=(float)s/n;
	cout<<m;
}