#include <bits/stdc++.h>
using namespace std;
int main(){
    int  m,n,i,h=0,a[n];
    float p=0;
    cin>>m>>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: linweilun
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2080 kb
****************************************************************/