#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr ll MOD = 1000000007;

int main(int argc, char **argv)
{
	ll a, b, c, d; cin >> a >> b >> c >> d;

	bool t{true};

	while (1)
	{
		if (t)
			c -= b;
		else
			a -= d;

		if (a == 0 || c == 0) break;
		t ^= true;
	}
	std::cout << (t ? "Yes" : "No")<< std::endl;
}