#include<bits/stdc++.h>
using namespace std;
int main()
{
    int m,n,i;
    float s=0;
    cin>>m>>n;
    int w[10];
    for(i=0;i<n;i++){
        cin>>w[i];
        s+=w[i];
    }
    s/=n;
    s*=m;
    printf("%.1f",s);
}
/**************************************************************
	Problem: 1316
	User: chenjiahui
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/