import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    int A = scanner.nextInt();
    int B = scanner.nextInt();
    int C = scanner.nextInt();
    int D = scanner.nextInt();
    if ((A + D - 1) / D >= (C + B - 1) / B) System.out.println("Yes");
    else {
      System.out.println("No");
    }
  }
} import java.util.Scanner; Scanner java.util public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    int A = scanner.nextInt();
    int B = scanner.nextInt();
    int C = scanner.nextInt();
    int D = scanner.nextInt();
    if ((A + D - 1) / D >= (C + B - 1) / B) System.out.println("Yes");
    else {
      System.out.println("No");
    }
  }
} Main public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    int A = scanner.nextInt();
    int B = scanner.nextInt();
    int C = scanner.nextInt();
    int D = scanner.nextInt();
    if ((A + D - 1) / D >= (C + B - 1) / B) System.out.println("Yes");
    else {
      System.out.println("No");
    }
  } main {
    Scanner scanner = new Scanner(System.in);

    int A = scanner.nextInt();
    int B = scanner.nextInt();
    int C = scanner.nextInt();
    int D = scanner.nextInt();
    if ((A + D - 1) / D >= (C + B - 1) / B) System.out.println("Yes");
    else {
      System.out.println("No");
    }
  } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int A = scanner.nextInt(); A scanner.nextInt() scanner.nextInt scanner int B = scanner.nextInt(); B scanner.nextInt() scanner.nextInt scanner int C = scanner.nextInt(); C scanner.nextInt() scanner.nextInt scanner int D = scanner.nextInt(); D scanner.nextInt() scanner.nextInt scanner if ((A + D - 1) / D >= (C + B - 1) / B) System.out.println("Yes");
    else {
      System.out.println("No");
    } (A + D - 1) / D >= (C + B - 1) / B (A + D - 1) / D (A + D - 1) A + D A D 1 D (C + B - 1) / B (C + B - 1) C + B C B 1 B System.out.println("Yes") System.out.println System.out System System.out "Yes" {
      System.out.println("No");
    } System.out.println("No") System.out.println System.out System System.out "No" String[] args args public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    int A = scanner.nextInt();
    int B = scanner.nextInt();
    int C = scanner.nextInt();
    int D = scanner.nextInt();
    if ((A + D - 1) / D >= (C + B - 1) / B) System.out.println("Yes");
    else {
      System.out.println("No");
    }
  }
} public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    int A = scanner.nextInt();
    int B = scanner.nextInt();
    int C = scanner.nextInt();
    int D = scanner.nextInt();
    if ((A + D - 1) / D >= (C + B - 1) / B) System.out.println("Yes");
    else {
      System.out.println("No");
    }
  }
} Main
import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    int A = scanner.nextInt();
    int B = scanner.nextInt();
    int C = scanner.nextInt();
    int D = scanner.nextInt();
    if ((A + D - 1) / D >= (C + B - 1) / B) System.out.println("Yes");
    else {
      System.out.println("No");
    }
  }
}
