import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
	
int A,B,C,D;

Scanner sc = new Scanner(System.in);
 A = sc.nextInt();

 B = sc.nextInt();

 C = sc.nextInt();

 D = sc.nextInt();

do {
	
	
	C=C-B;
	if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	}
	A=A-D;
	if(A<=0) {
		System.out.println("No");
		System.exit(0);
	}
}
while(true);
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
	
int A,B,C,D;

Scanner sc = new Scanner(System.in);
 A = sc.nextInt();

 B = sc.nextInt();

 C = sc.nextInt();

 D = sc.nextInt();

do {
	
	
	C=C-B;
	if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	}
	A=A-D;
	if(A<=0) {
		System.out.println("No");
		System.exit(0);
	}
}
while(true);
	}
} Main public static void main(String[] args) {
	
int A,B,C,D;

Scanner sc = new Scanner(System.in);
 A = sc.nextInt();

 B = sc.nextInt();

 C = sc.nextInt();

 D = sc.nextInt();

do {
	
	
	C=C-B;
	if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	}
	A=A-D;
	if(A<=0) {
		System.out.println("No");
		System.exit(0);
	}
}
while(true);
	} main {
	
int A,B,C,D;

Scanner sc = new Scanner(System.in);
 A = sc.nextInt();

 B = sc.nextInt();

 C = sc.nextInt();

 D = sc.nextInt();

do {
	
	
	C=C-B;
	if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	}
	A=A-D;
	if(A<=0) {
		System.out.println("No");
		System.exit(0);
	}
}
while(true);
	} int A A B B C C D; D Scanner sc = new Scanner(System.in); sc new Scanner(System.in) A = sc.nextInt() A sc.nextInt() sc.nextInt sc B = sc.nextInt() B sc.nextInt() sc.nextInt sc C = sc.nextInt() C sc.nextInt() sc.nextInt sc D = sc.nextInt() D sc.nextInt() sc.nextInt sc do {
	
	
	C=C-B;
	if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	}
	A=A-D;
	if(A<=0) {
		System.out.println("No");
		System.exit(0);
	}
}
while(true); true {
	
	
	C=C-B;
	if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	}
	A=A-D;
	if(A<=0) {
		System.out.println("No");
		System.exit(0);
	}
} C=C-B C C-B C B if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	} C<=0 C 0 {
		System.out.println("Yes");
		System.exit(0);
	} System.out.println("Yes") System.out.println System.out System System.out "Yes" System.exit(0) System.exit System 0 A=A-D A A-D A D if(A<=0) {
		System.out.println("No");
		System.exit(0);
	} A<=0 A 0 {
		System.out.println("No");
		System.exit(0);
	} System.out.println("No") System.out.println System.out System System.out "No" System.exit(0) System.exit System 0 String[] args args public class Main {

	public static void main(String[] args) {
	
int A,B,C,D;

Scanner sc = new Scanner(System.in);
 A = sc.nextInt();

 B = sc.nextInt();

 C = sc.nextInt();

 D = sc.nextInt();

do {
	
	
	C=C-B;
	if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	}
	A=A-D;
	if(A<=0) {
		System.out.println("No");
		System.exit(0);
	}
}
while(true);
	}
} public class Main {

	public static void main(String[] args) {
	
int A,B,C,D;

Scanner sc = new Scanner(System.in);
 A = sc.nextInt();

 B = sc.nextInt();

 C = sc.nextInt();

 D = sc.nextInt();

do {
	
	
	C=C-B;
	if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	}
	A=A-D;
	if(A<=0) {
		System.out.println("No");
		System.exit(0);
	}
}
while(true);
	}
} Main
import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
	
int A,B,C,D;

Scanner sc = new Scanner(System.in);
 A = sc.nextInt();

 B = sc.nextInt();

 C = sc.nextInt();

 D = sc.nextInt();

do {
	
	
	C=C-B;
	if(C<=0) {
		System.out.println("Yes");
		System.exit(0);
	}
	A=A-D;
	if(A<=0) {
		System.out.println("No");
		System.exit(0);
	}
}
while(true);
	}
}