#include <bits/stdc++.h>
using namespace std;
int main(){
	float j=0,d=0;
	int a,i,x=0,m;
	cin>>m;
	cin>>a;
	int n[a]={0};
	for(i=0;i<a;i++){
		cin>>n[i];
		j=j+n[i];
	}
	d=j*1.0/a*m;
	printf("%.1f",d);
}

/**************************************************************
	Problem: 1316
	User: 15159808820
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/