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();
    
    double X = Math.ceil((double)C/(double)B);
    double Y = Math.ceil((double)A/(double)D);
    
    if(X <= Y){
      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();
    
    double X = Math.ceil((double)C/(double)B);
    double Y = Math.ceil((double)A/(double)D);
    
    if(X <= Y){
      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();
    
    double X = Math.ceil((double)C/(double)B);
    double Y = Math.ceil((double)A/(double)D);
    
    if(X <= Y){
      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();
    
    double X = Math.ceil((double)C/(double)B);
    double Y = Math.ceil((double)A/(double)D);
    
    if(X <= Y){
      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 double X = Math.ceil((double)C/(double)B); X Math.ceil((double)C/(double)B) Math.ceil Math (double)C/(double)B (double)C (double)B double Y = Math.ceil((double)A/(double)D); Y Math.ceil((double)A/(double)D) Math.ceil Math (double)A/(double)D (double)A (double)D if(X <= Y){
      System.out.println("Yes");
    }else{
      System.out.println("No");
    } X <= Y X Y {
      System.out.println("Yes");
    } 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();
    
    double X = Math.ceil((double)C/(double)B);
    double Y = Math.ceil((double)A/(double)D);
    
    if(X <= Y){
      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();
    
    double X = Math.ceil((double)C/(double)B);
    double Y = Math.ceil((double)A/(double)D);
    
    if(X <= Y){
      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();
    
    double X = Math.ceil((double)C/(double)B);
    double Y = Math.ceil((double)A/(double)D);
    
    if(X <= Y){
      System.out.println("Yes");
    }else{
      System.out.println("No");
    }
  }
}

    
    
