import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    int x = (a+d-1)/d;
    int y = (c+b-1)/b;
    System.out.println(x>=y?"Yes":"No");
  }
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.IOException; IOException java.io public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    int x = (a+d-1)/d;
    int y = (c+b-1)/b;
    System.out.println(x>=y?"Yes":"No");
  }
} Main public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    int x = (a+d-1)/d;
    int y = (c+b-1)/b;
    System.out.println(x>=y?"Yes":"No");
  } main {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    int x = (a+d-1)/d;
    int y = (c+b-1)/b;
    System.out.println(x>=y?"Yes":"No");
  } BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in new BufferedReader(new InputStreamReader(System.in)) String[] str = in.readLine().split(" "); str in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " int a = Integer.parseInt(str[0]); a Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int b = Integer.parseInt(str[1]); b Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 int c = Integer.parseInt(str[2]); c Integer.parseInt(str[2]) Integer.parseInt Integer str[2] str 2 int d = Integer.parseInt(str[3]); d Integer.parseInt(str[3]) Integer.parseInt Integer str[3] str 3 int x = (a+d-1)/d; x (a+d-1)/d (a+d-1) a+d a d 1 d int y = (c+b-1)/b; y (c+b-1)/b (c+b-1) c+b c b 1 b System.out.println(x>=y?"Yes":"No") System.out.println System.out System System.out x>=y?"Yes":"No" x>=y x y "Yes" "No" String[] args args public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    int x = (a+d-1)/d;
    int y = (c+b-1)/b;
    System.out.println(x>=y?"Yes":"No");
  }
} public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    int x = (a+d-1)/d;
    int y = (c+b-1)/b;
    System.out.println(x>=y?"Yes":"No");
  }
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String[] str = in.readLine().split(" ");
    int a = Integer.parseInt(str[0]);
    int b = Integer.parseInt(str[1]);
    int c = Integer.parseInt(str[2]);
    int d = Integer.parseInt(str[3]);
    int x = (a+d-1)/d;
    int y = (c+b-1)/b;
    System.out.println(x>=y?"Yes":"No");
  }
}