
import java.util.*;
import java.util.ArrayDeque;
import java.util.Queue;
import java.math.RoundingMode;
import java.math.BigDecimal;



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();
	   	while(a>0&&c>0) {
	   		a=a-d;
	   		c=c-b;
	   	}
	   	if(a<=0&&c<=0) {
	   		System.out.println("Yes");
	   	}
	   	else if(a<=0&&c>0) {
	   		System.out.println("No");
	   	}
	   	else if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	}
	 }
} import java.util.*; util.* java import java.util.ArrayDeque; ArrayDeque java.util import java.util.Queue; Queue java.util import java.math.RoundingMode; RoundingMode java.math import java.math.BigDecimal; BigDecimal java.math 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();
	   	while(a>0&&c>0) {
	   		a=a-d;
	   		c=c-b;
	   	}
	   	if(a<=0&&c<=0) {
	   		System.out.println("Yes");
	   	}
	   	else if(a<=0&&c>0) {
	   		System.out.println("No");
	   	}
	   	else if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	}
	 }
} 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();
	   	while(a>0&&c>0) {
	   		a=a-d;
	   		c=c-b;
	   	}
	   	if(a<=0&&c<=0) {
	   		System.out.println("Yes");
	   	}
	   	else if(a<=0&&c>0) {
	   		System.out.println("No");
	   	}
	   	else if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	}
	 } main {
		Scanner sc = new Scanner(System.in);
	   	int a = sc.nextInt();
	   	int b = sc.nextInt();
	   	int c = sc.nextInt();
	   	int d = sc.nextInt();
	   	while(a>0&&c>0) {
	   		a=a-d;
	   		c=c-b;
	   	}
	   	if(a<=0&&c<=0) {
	   		System.out.println("Yes");
	   	}
	   	else if(a<=0&&c>0) {
	   		System.out.println("No");
	   	}
	   	else if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	}
	 } 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 while(a>0&&c>0) {
	   		a=a-d;
	   		c=c-b;
	   	} a>0&&c>0 a>0 a 0 c>0 c 0 {
	   		a=a-d;
	   		c=c-b;
	   	} a=a-d a a-d a d c=c-b c c-b c b if(a<=0&&c<=0) {
	   		System.out.println("Yes");
	   	}
	   	else if(a<=0&&c>0) {
	   		System.out.println("No");
	   	}
	   	else if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	} a<=0&&c<=0 a<=0 a 0 c<=0 c 0 {
	   		System.out.println("Yes");
	   	} System.out.println("Yes") System.out.println System.out System System.out "Yes" if(a<=0&&c>0) {
	   		System.out.println("No");
	   	}
	   	else if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	} a<=0&&c>0 a<=0 a 0 c>0 c 0 {
	   		System.out.println("No");
	   	} System.out.println("No") System.out.println System.out System System.out "No" if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	} c<=0&&a>0 c<=0 c 0 a>0 a 0 {
	   		System.out.println("Yes");
	   	} System.out.println("Yes") System.out.println System.out System System.out "Yes" 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();
	   	while(a>0&&c>0) {
	   		a=a-d;
	   		c=c-b;
	   	}
	   	if(a<=0&&c<=0) {
	   		System.out.println("Yes");
	   	}
	   	else if(a<=0&&c>0) {
	   		System.out.println("No");
	   	}
	   	else if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	}
	 }
} 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();
	   	while(a>0&&c>0) {
	   		a=a-d;
	   		c=c-b;
	   	}
	   	if(a<=0&&c<=0) {
	   		System.out.println("Yes");
	   	}
	   	else if(a<=0&&c>0) {
	   		System.out.println("No");
	   	}
	   	else if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	}
	 }
} Main

import java.util.*;
import java.util.ArrayDeque;
import java.util.Queue;
import java.math.RoundingMode;
import java.math.BigDecimal;



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();
	   	while(a>0&&c>0) {
	   		a=a-d;
	   		c=c-b;
	   	}
	   	if(a<=0&&c<=0) {
	   		System.out.println("Yes");
	   	}
	   	else if(a<=0&&c>0) {
	   		System.out.println("No");
	   	}
	   	else if(c<=0&&a>0) {
	   		System.out.println("Yes");
	   	}
	 }
}