import java.util.Scanner;

public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    
    int tHp = scan.nextInt();
    int tAt = scan.nextInt();
    int aHp = scan.nextInt();
    int aAt = scan.nextInt();
    
    for(int i = 0; i <200; i++){
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 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 tHp = scan.nextInt();
    int tAt = scan.nextInt();
    int aHp = scan.nextInt();
    int aAt = scan.nextInt();
    
    for(int i = 0; i <200; i++){
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 0){
        System.out.println("No");
        break;
      }
    }
  }
} Main public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    
    int tHp = scan.nextInt();
    int tAt = scan.nextInt();
    int aHp = scan.nextInt();
    int aAt = scan.nextInt();
    
    for(int i = 0; i <200; i++){
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 0){
        System.out.println("No");
        break;
      }
    }
  } main {
    Scanner scan = new Scanner(System.in);
    
    int tHp = scan.nextInt();
    int tAt = scan.nextInt();
    int aHp = scan.nextInt();
    int aAt = scan.nextInt();
    
    for(int i = 0; i <200; i++){
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 0){
        System.out.println("No");
        break;
      }
    }
  } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int tHp = scan.nextInt(); tHp scan.nextInt() scan.nextInt scan int tAt = scan.nextInt(); tAt scan.nextInt() scan.nextInt scan int aHp = scan.nextInt(); aHp scan.nextInt() scan.nextInt scan int aAt = scan.nextInt(); aAt scan.nextInt() scan.nextInt scan for(int i = 0; i <200; i++){
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 0){
        System.out.println("No");
        break;
      }
    } int i = 0; int i = 0; i 0 i <200 i 200 i++ i++ i {
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 0){
        System.out.println("No");
        break;
      }
    } {
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 0){
        System.out.println("No");
        break;
      }
    } if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt; i%2 == 0 i%2 i 2 0 aHp = aHp - tAt aHp aHp - tAt aHp tAt tHp = tHp - aAt tHp tHp - aAt tHp aAt if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 0){
        System.out.println("No");
        break;
      } aHp <=0 aHp 0 {
        System.out.println("Yes");
        break;
      } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; if(tHp <= 0){
        System.out.println("No");
        break;
      } tHp <= 0 tHp 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 tHp = scan.nextInt();
    int tAt = scan.nextInt();
    int aHp = scan.nextInt();
    int aAt = scan.nextInt();
    
    for(int i = 0; i <200; i++){
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 0){
        System.out.println("No");
        break;
      }
    }
  }
} public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    
    int tHp = scan.nextInt();
    int tAt = scan.nextInt();
    int aHp = scan.nextInt();
    int aAt = scan.nextInt();
    
    for(int i = 0; i <200; i++){
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 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 tHp = scan.nextInt();
    int tAt = scan.nextInt();
    int aHp = scan.nextInt();
    int aAt = scan.nextInt();
    
    for(int i = 0; i <200; i++){
      if(i%2 == 0)
        aHp = aHp - tAt;
      else
        tHp = tHp - aAt;
      
      if(aHp <=0 ){
        System.out.println("Yes");
        break;
      }
      else if(tHp <= 0){
        System.out.println("No");
        break;
      }
    }
  }
}
      
