import java.io.*;
import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		// ------------------------------------------------

		int a, b, c, d;
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		c = Integer.parseInt(sc.next());
		d = Integer.parseInt(sc.next());

		boolean takaWin = false;
		while (true) {
			c -= b;
			if (c <= 0) {
				takaWin = true;
				break;
			}
			a -= d;
			if (a <= 0) {
				takaWin = false;
				break;
			}
		}
		if (takaWin) {
			out.println("Yes");
		} else {
			out.println("No");
		}

		// ------------------------------------------------
		sc.close();
		out.flush();
	}
} import java.io.*; io.* java import java.util.*; util.* java public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		// ------------------------------------------------

		int a, b, c, d;
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		c = Integer.parseInt(sc.next());
		d = Integer.parseInt(sc.next());

		boolean takaWin = false;
		while (true) {
			c -= b;
			if (c <= 0) {
				takaWin = true;
				break;
			}
			a -= d;
			if (a <= 0) {
				takaWin = false;
				break;
			}
		}
		if (takaWin) {
			out.println("Yes");
		} else {
			out.println("No");
		}

		// ------------------------------------------------
		sc.close();
		out.flush();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		// ------------------------------------------------

		int a, b, c, d;
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		c = Integer.parseInt(sc.next());
		d = Integer.parseInt(sc.next());

		boolean takaWin = false;
		while (true) {
			c -= b;
			if (c <= 0) {
				takaWin = true;
				break;
			}
			a -= d;
			if (a <= 0) {
				takaWin = false;
				break;
			}
		}
		if (takaWin) {
			out.println("Yes");
		} else {
			out.println("No");
		}

		// ------------------------------------------------
		sc.close();
		out.flush();
	} main {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		// ------------------------------------------------

		int a, b, c, d;
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		c = Integer.parseInt(sc.next());
		d = Integer.parseInt(sc.next());

		boolean takaWin = false;
		while (true) {
			c -= b;
			if (c <= 0) {
				takaWin = true;
				break;
			}
			a -= d;
			if (a <= 0) {
				takaWin = false;
				break;
			}
		}
		if (takaWin) {
			out.println("Yes");
		} else {
			out.println("No");
		}

		// ------------------------------------------------
		sc.close();
		out.flush();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) int a a b b c c d; d a = Integer.parseInt(sc.next()) a Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc b = Integer.parseInt(sc.next()) b Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc c = Integer.parseInt(sc.next()) c Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc d = Integer.parseInt(sc.next()) d Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc boolean takaWin = false; takaWin false while (true) {
			c -= b;
			if (c <= 0) {
				takaWin = true;
				break;
			}
			a -= d;
			if (a <= 0) {
				takaWin = false;
				break;
			}
		} true {
			c -= b;
			if (c <= 0) {
				takaWin = true;
				break;
			}
			a -= d;
			if (a <= 0) {
				takaWin = false;
				break;
			}
		} c -= b c b if (c <= 0) {
				takaWin = true;
				break;
			} c <= 0 c 0 {
				takaWin = true;
				break;
			} takaWin = true takaWin true break; a -= d a d if (a <= 0) {
				takaWin = false;
				break;
			} a <= 0 a 0 {
				takaWin = false;
				break;
			} takaWin = false takaWin false break; if (takaWin) {
			out.println("Yes");
		} else {
			out.println("No");
		} takaWin {
			out.println("Yes");
		} out.println("Yes") out.println out "Yes" {
			out.println("No");
		} out.println("No") out.println out "No" sc.close() sc.close sc out.flush() out.flush out String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		// ------------------------------------------------

		int a, b, c, d;
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		c = Integer.parseInt(sc.next());
		d = Integer.parseInt(sc.next());

		boolean takaWin = false;
		while (true) {
			c -= b;
			if (c <= 0) {
				takaWin = true;
				break;
			}
			a -= d;
			if (a <= 0) {
				takaWin = false;
				break;
			}
		}
		if (takaWin) {
			out.println("Yes");
		} else {
			out.println("No");
		}

		// ------------------------------------------------
		sc.close();
		out.flush();
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		// ------------------------------------------------

		int a, b, c, d;
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		c = Integer.parseInt(sc.next());
		d = Integer.parseInt(sc.next());

		boolean takaWin = false;
		while (true) {
			c -= b;
			if (c <= 0) {
				takaWin = true;
				break;
			}
			a -= d;
			if (a <= 0) {
				takaWin = false;
				break;
			}
		}
		if (takaWin) {
			out.println("Yes");
		} else {
			out.println("No");
		}

		// ------------------------------------------------
		sc.close();
		out.flush();
	}
} Main
import java.io.*;
import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		// ------------------------------------------------

		int a, b, c, d;
		a = Integer.parseInt(sc.next());
		b = Integer.parseInt(sc.next());
		c = Integer.parseInt(sc.next());
		d = Integer.parseInt(sc.next());

		boolean takaWin = false;
		while (true) {
			c -= b;
			if (c <= 0) {
				takaWin = true;
				break;
			}
			a -= d;
			if (a <= 0) {
				takaWin = false;
				break;
			}
		}
		if (takaWin) {
			out.println("Yes");
		} else {
			out.println("No");
		}

		// ------------------------------------------------
		sc.close();
		out.flush();
	}
}