#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

int n;
double num,r,sum;

int main()
{
    cin>>n>>r;
    for(int i=0;i<=n;i++){
        cin>>num;
        int j=i;
        while(j--){
            num/=(1+r);
        }
        sum+=num;
    }
    cout<<sum;
}