#include <bits/stdc++.h>   using namespace std;   int main() {     float num;     int t, n, d;     cin >> num >> t >> n >> d;     int a = (num / n);     if ((num / n) > a) a += 1;     int y = d, x = 0;     for (int i = 0; i < a; i++) {       if (x <= y)         x += t;       else         y += t;     }     if (max(x, y) < (t * a))       cout <<  YES ;     else       cout <<  NO ;     return 0;   }   