import java.util.*;

public class Main {
  public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int hp1 = sc.nextInt();
          int attack1 = sc.nextInt();
          int hp2 = sc.nextInt();
          int attack2 = sc.nextInt();
          while(hp1 > 0 && hp2 > 0){
            hp2 -= attack1;
          if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          }
            hp1 -= attack2;
          if(hp1 <= 0) {
            System.out.println("No");
            continue;
          }
          }
          }
        } import java.util.*; util.* java public class Main {
  public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int hp1 = sc.nextInt();
          int attack1 = sc.nextInt();
          int hp2 = sc.nextInt();
          int attack2 = sc.nextInt();
          while(hp1 > 0 && hp2 > 0){
            hp2 -= attack1;
          if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          }
            hp1 -= attack2;
          if(hp1 <= 0) {
            System.out.println("No");
            continue;
          }
          }
          }
        } Main public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int hp1 = sc.nextInt();
          int attack1 = sc.nextInt();
          int hp2 = sc.nextInt();
          int attack2 = sc.nextInt();
          while(hp1 > 0 && hp2 > 0){
            hp2 -= attack1;
          if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          }
            hp1 -= attack2;
          if(hp1 <= 0) {
            System.out.println("No");
            continue;
          }
          }
          } main {
          Scanner sc = new Scanner(System.in);
          int hp1 = sc.nextInt();
          int attack1 = sc.nextInt();
          int hp2 = sc.nextInt();
          int attack2 = sc.nextInt();
          while(hp1 > 0 && hp2 > 0){
            hp2 -= attack1;
          if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          }
            hp1 -= attack2;
          if(hp1 <= 0) {
            System.out.println("No");
            continue;
          }
          }
          } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int hp1 = sc.nextInt(); hp1 sc.nextInt() sc.nextInt sc int attack1 = sc.nextInt(); attack1 sc.nextInt() sc.nextInt sc int hp2 = sc.nextInt(); hp2 sc.nextInt() sc.nextInt sc int attack2 = sc.nextInt(); attack2 sc.nextInt() sc.nextInt sc while(hp1 > 0 && hp2 > 0){
            hp2 -= attack1;
          if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          }
            hp1 -= attack2;
          if(hp1 <= 0) {
            System.out.println("No");
            continue;
          }
          } hp1 > 0 && hp2 > 0 hp1 > 0 hp1 0 hp2 > 0 hp2 0 {
            hp2 -= attack1;
          if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          }
            hp1 -= attack2;
          if(hp1 <= 0) {
            System.out.println("No");
            continue;
          }
          } hp2 -= attack1 hp2 attack1 if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          } hp2 <= 0 hp2 0 {
            System.out.println("Yes");
            continue;
          } System.out.println("Yes") System.out.println System.out System System.out "Yes" continue; hp1 -= attack2 hp1 attack2 if(hp1 <= 0) {
            System.out.println("No");
            continue;
          } hp1 <= 0 hp1 0 {
            System.out.println("No");
            continue;
          } System.out.println("No") System.out.println System.out System System.out "No" continue; String[] args args public class Main {
  public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int hp1 = sc.nextInt();
          int attack1 = sc.nextInt();
          int hp2 = sc.nextInt();
          int attack2 = sc.nextInt();
          while(hp1 > 0 && hp2 > 0){
            hp2 -= attack1;
          if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          }
            hp1 -= attack2;
          if(hp1 <= 0) {
            System.out.println("No");
            continue;
          }
          }
          }
        } public class Main {
  public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int hp1 = sc.nextInt();
          int attack1 = sc.nextInt();
          int hp2 = sc.nextInt();
          int attack2 = sc.nextInt();
          while(hp1 > 0 && hp2 > 0){
            hp2 -= attack1;
          if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          }
            hp1 -= attack2;
          if(hp1 <= 0) {
            System.out.println("No");
            continue;
          }
          }
          }
        } Main
import java.util.*;

public class Main {
  public static void main(String[] args) {
          Scanner sc = new Scanner(System.in);
          int hp1 = sc.nextInt();
          int attack1 = sc.nextInt();
          int hp2 = sc.nextInt();
          int attack2 = sc.nextInt();
          while(hp1 > 0 && hp2 > 0){
            hp2 -= attack1;
          if(hp2 <= 0) {
            System.out.println("Yes");
            continue;
          }
            hp1 -= attack2;
          if(hp1 <= 0) {
            System.out.println("No");
            continue;
          }
          }
          }
        }