import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int a = scan.nextInt();
    int b = scan.nextInt();
    int c = scan.nextInt();
    int d = scan.nextInt();
    for (int i = 0; i < 1000; i++){
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    }
  }
} import java.util.Scanner; Scanner java.util public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int a = scan.nextInt();
    int b = scan.nextInt();
    int c = scan.nextInt();
    int d = scan.nextInt();
    for (int i = 0; i < 1000; i++){
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    }
  }
} Main public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int a = scan.nextInt();
    int b = scan.nextInt();
    int c = scan.nextInt();
    int d = scan.nextInt();
    for (int i = 0; i < 1000; i++){
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    }
  } main {
    Scanner scan = new Scanner(System.in);
    int a = scan.nextInt();
    int b = scan.nextInt();
    int c = scan.nextInt();
    int d = scan.nextInt();
    for (int i = 0; i < 1000; i++){
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    }
  } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int a = scan.nextInt(); a scan.nextInt() scan.nextInt scan int b = scan.nextInt(); b scan.nextInt() scan.nextInt scan int c = scan.nextInt(); c scan.nextInt() scan.nextInt scan int d = scan.nextInt(); d scan.nextInt() scan.nextInt scan for (int i = 0; i < 1000; i++){
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    } int i = 0; int i = 0; i 0 i < 1000 i 1000 i++ i++ i {
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    } {
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    } c -= b c b if (c <= 0){
        System.out.println("Yes");
        break;
      } c <= 0 c 0 {
        System.out.println("Yes");
        break;
      } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; a -= d a d if (a <= 0){
        System.out.println("No");
        break;
      } a <= 0 a 0 {
        System.out.println("No");
        break;
      } System.out.println("No") System.out.println System.out System System.out "No" break; String[] args args public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int a = scan.nextInt();
    int b = scan.nextInt();
    int c = scan.nextInt();
    int d = scan.nextInt();
    for (int i = 0; i < 1000; i++){
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    }
  }
} public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int a = scan.nextInt();
    int b = scan.nextInt();
    int c = scan.nextInt();
    int d = scan.nextInt();
    for (int i = 0; i < 1000; i++){
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    }
  }
} Main
import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int a = scan.nextInt();
    int b = scan.nextInt();
    int c = scan.nextInt();
    int d = scan.nextInt();
    for (int i = 0; i < 1000; i++){
      c -= b;
      if (c <= 0){
        System.out.println("Yes");
        break;
      }
      a -= d;
      if (a <= 0){
        System.out.println("No");
        break;
      }
    }
  }
}
