import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
			String[] s = br.readLine().split(" ");
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			}
		}
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
			String[] s = br.readLine().split(" ");
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			}
		}
	}
} Main public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
			String[] s = br.readLine().split(" ");
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			}
		}
	} main {
		try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
			String[] s = br.readLine().split(" ");
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			}
		}
	} try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
			String[] s = br.readLine().split(" ");
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			}
		} {
			String[] s = br.readLine().split(" ");
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			}
		} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)) BufferedReader br = new BufferedReader(new InputStreamReader(System.in)) new BufferedReader(new InputStreamReader(System.in)) String[] s = br.readLine().split(" "); s br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int a = Integer.parseInt(s[0]); a Integer.parseInt(s[0]) Integer.parseInt Integer s[0] s 0 int b = Integer.parseInt(s[1]); b Integer.parseInt(s[1]) Integer.parseInt Integer s[1] s 1 int c = Integer.parseInt(s[2]); c Integer.parseInt(s[2]) Integer.parseInt Integer s[2] s 2 int d = Integer.parseInt(s[3]); d Integer.parseInt(s[3]) Integer.parseInt Integer s[3] s 3 while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			} true {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			} c -= b c b if (c <= 0) {
					System.out.println("Yes");
					return;
				} c <= 0 c 0 {
					System.out.println("Yes");
					return;
				} System.out.println("Yes") System.out.println System.out System System.out "Yes" return; a -= d a d if (a <= 0) {
					System.out.println("No");
					return;
				} a <= 0 a 0 {
					System.out.println("No");
					return;
				} System.out.println("No") System.out.println System.out System System.out "No" return; String[] args args public class Main {
	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
			String[] s = br.readLine().split(" ");
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			}
		}
	}
} public class Main {
	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
			String[] s = br.readLine().split(" ");
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			}
		}
	}
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
			String[] s = br.readLine().split(" ");
			int a = Integer.parseInt(s[0]);
			int b = Integer.parseInt(s[1]);
			int c = Integer.parseInt(s[2]);
			int d = Integer.parseInt(s[3]);
			while (true) {
				c -= b;
				if (c <= 0) {
					System.out.println("Yes");
					return;
				}
				a -= d;
				if (a <= 0) {
					System.out.println("No");
					return;
				}
			}
		}
	}
}