#include <bits/stdc++.h>
using namespace std;
int main(){
	int  m,n,i,h=0;
	float p=0;
	cin>>m>>n;
	int a[n];
	for(i=0;i<n;i++){
		cin>>a[i];
		h=h+a[i];
	}
	p=h*1.0/n;
	printf("%.1f",p*m);
	
	
}
/**************************************************************
	Problem: 1316
	User: linzihang
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/