#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,a[10],m;
	float u=0;
	cin>>m>>n;
	for(int i=0;i<=n-1;i++){
		cin>>a[i];
		u+=a[i];
	}
	u/=n;
	u*=m;
	printf("%.1f",u);
	return 0;
}

/**************************************************************
	Problem: 1316
	User: houshanglin
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/