#include using namespace std; #define ll long long #define rep(i, n) for (int i = 0; i < (n); i++) #define P pair ll l, r, m, k; void solve() { cin >> l >> r >> m >> k; if (k == 0 || l == 0 || m == 1) { cout << "Yes" << endl; return; } if (l == r) { if ((l*k)%m==0) cout << "Yes" << endl; else cout << "No" << endl; return; } string ans = "No"; if ((r-l)*k >= m) { ans = "Yes"; } else { if ((r*k)%m < (l*k)%m) ans = "Yes"; } cout << ans << endl; } int main() { solve(); }