#include <iostream>
using namespace std;

int main()
{
  float V, T, S, D;
  scanf("%f %f %f %f", &V, &T, &S, &D);
  float s = D / V;
  if ((T <= s) & (s <= S)) {
    printf("No");
  }
  else {
    printf("Yes");
  }
}
#include <bits/stdc++.h>
using namespace std;
#define ll long long int 

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    #ifndef ONLINE_JUDGE 
    freopen("input.txt", "r", stdin); 
    freopen("output.txt", "w", stdout); 
    #endif
    int t=1;
    //cin>>t;
    while(t--)
    {
      int n;
      cin>>n;
      if(n%2) cout<<"Black";
      else cout<<"White";
    }
}
