import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int TH = sc.nextInt();
		int TA = sc.nextInt();
		int AH = sc.nextInt();
		int AA = sc.nextInt();
		int turn = 1;

		while (TH > 0 && AH > 0) {
			if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			}
			turn++;
		}

		if (TH <= 0) {
			System.out.println("No");
		}else {
			System.out.println("Yes");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int TH = sc.nextInt();
		int TA = sc.nextInt();
		int AH = sc.nextInt();
		int AA = sc.nextInt();
		int turn = 1;

		while (TH > 0 && AH > 0) {
			if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			}
			turn++;
		}

		if (TH <= 0) {
			System.out.println("No");
		}else {
			System.out.println("Yes");
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int TH = sc.nextInt();
		int TA = sc.nextInt();
		int AH = sc.nextInt();
		int AA = sc.nextInt();
		int turn = 1;

		while (TH > 0 && AH > 0) {
			if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			}
			turn++;
		}

		if (TH <= 0) {
			System.out.println("No");
		}else {
			System.out.println("Yes");
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int TH = sc.nextInt();
		int TA = sc.nextInt();
		int AH = sc.nextInt();
		int AA = sc.nextInt();
		int turn = 1;

		while (TH > 0 && AH > 0) {
			if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			}
			turn++;
		}

		if (TH <= 0) {
			System.out.println("No");
		}else {
			System.out.println("Yes");
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int TH = sc.nextInt(); TH sc.nextInt() sc.nextInt sc int TA = sc.nextInt(); TA sc.nextInt() sc.nextInt sc int AH = sc.nextInt(); AH sc.nextInt() sc.nextInt sc int AA = sc.nextInt(); AA sc.nextInt() sc.nextInt sc int turn = 1; turn 1 while (TH > 0 && AH > 0) {
			if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			}
			turn++;
		} TH > 0 && AH > 0 TH > 0 TH 0 AH > 0 AH 0 {
			if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			}
			turn++;
		} if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			} turn % 2 == 1 turn % 2 turn 2 1 {
				AH = AH - TA;
			} AH = AH - TA AH AH - TA AH TA {
				TH = TH - AA;
			} TH = TH - AA TH TH - AA TH AA turn++ turn if (TH <= 0) {
			System.out.println("No");
		}else {
			System.out.println("Yes");
		} TH <= 0 TH 0 {
			System.out.println("No");
		} System.out.println("No") System.out.println System.out System System.out "No" {
			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 TH = sc.nextInt();
		int TA = sc.nextInt();
		int AH = sc.nextInt();
		int AA = sc.nextInt();
		int turn = 1;

		while (TH > 0 && AH > 0) {
			if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			}
			turn++;
		}

		if (TH <= 0) {
			System.out.println("No");
		}else {
			System.out.println("Yes");
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int TH = sc.nextInt();
		int TA = sc.nextInt();
		int AH = sc.nextInt();
		int AA = sc.nextInt();
		int turn = 1;

		while (TH > 0 && AH > 0) {
			if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			}
			turn++;
		}

		if (TH <= 0) {
			System.out.println("No");
		}else {
			System.out.println("Yes");
		}
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int TH = sc.nextInt();
		int TA = sc.nextInt();
		int AH = sc.nextInt();
		int AA = sc.nextInt();
		int turn = 1;

		while (TH > 0 && AH > 0) {
			if (turn % 2 == 1) {
				AH = AH - TA;
			} else {
				TH = TH - AA;
			}
			turn++;
		}

		if (TH <= 0) {
			System.out.println("No");
		}else {
			System.out.println("Yes");
		}
	}
}
