#include <bits/stdc++.h>

#define rep(i, n) for (int (i) = 0; (i) < (int)(n); (i)++)

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
using namespace std;
typedef long long ll;

int main() {
    ll H, W, N, K;
    cin >> H >> W >> N >> K;
    ll hw = H*W;
    ll p = hw % N;
    string ans;
    if (p == 0) {
        if (K == N) ans = "YES";
        else ans = "NO";
    } else {
        if (p == K) ans = "YES";
        else ans = "NO";
    }
    cout << ans << endl;
    return 0;
}