import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int d = sc.nextInt();
    int z =0;
    if((a+d-1)/d>=(c+b-1)/b){
      System.out.println("Yes");
    }
    else{
      System.out.println("No");
    }
  }
} import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int d = sc.nextInt();
    int z =0;
    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 sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int d = sc.nextInt();
    int z =0;
    if((a+d-1)/d>=(c+b-1)/b){
      System.out.println("Yes");
    }
    else{
      System.out.println("No");
    }
  } main {
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int d = sc.nextInt();
    int z =0;
    if((a+d-1)/d>=(c+b-1)/b){
      System.out.println("Yes");
    }
    else{
      System.out.println("No");
    }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int c = sc.nextInt(); c sc.nextInt() sc.nextInt sc int d = sc.nextInt(); d sc.nextInt() sc.nextInt sc int z =0; z 0 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("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 sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int d = sc.nextInt();
    int z =0;
    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 sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int d = sc.nextInt();
    int z =0;
    if((a+d-1)/d>=(c+b-1)/b){
      System.out.println("Yes");
    }
    else{
      System.out.println("No");
    }
  }
} Main
import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();
    int d = sc.nextInt();
    int z =0;
    if((a+d-1)/d>=(c+b-1)/b){
      System.out.println("Yes");
    }
    else{
      System.out.println("No");
    }
  }
}