import java.io.*;

public class Main {
	static Reader in = new InputStreamReader(System.in);
	static Writer out = new PrintWriter(System.out);

	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			}
			out.close();
		}
	}

} import java.io.*; io.* java public class Main {
	static Reader in = new InputStreamReader(System.in);
	static Writer out = new PrintWriter(System.out);

	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			}
			out.close();
		}
	}

} Main static Reader in = new InputStreamReader(System.in); in new InputStreamReader(System.in) static Writer out = new PrintWriter(System.out); out new PrintWriter(System.out) public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			}
			out.close();
		}
	} main {
		try (BufferedReader br = new BufferedReader(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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			}
			out.close();
		}
	} try (BufferedReader br = new BufferedReader(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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			}
			out.close();
		} {
			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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			}
			out.close();
		} BufferedReader br = new BufferedReader(in) BufferedReader br = new BufferedReader(in) new BufferedReader(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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			} true {
				c -= b;
				if (c <= 0) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			} c -= b c b if (c <= 0) {
					out.write("Yes");
					break;
				} c <= 0 c 0 {
					out.write("Yes");
					break;
				} out.write("Yes") out.write out "Yes" break; a -= d a d if (a <= 0) {
					out.write("No");
					break;
				} a <= 0 a 0 {
					out.write("No");
					break;
				} out.write("No") out.write out "No" break; out.close() out.close out String[] args args public class Main {
	static Reader in = new InputStreamReader(System.in);
	static Writer out = new PrintWriter(System.out);

	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			}
			out.close();
		}
	}

} public class Main {
	static Reader in = new InputStreamReader(System.in);
	static Writer out = new PrintWriter(System.out);

	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			}
			out.close();
		}
	}

} Main
import java.io.*;

public class Main {
	static Reader in = new InputStreamReader(System.in);
	static Writer out = new PrintWriter(System.out);

	public static void main(String[] args) throws Exception {
		try (BufferedReader br = new BufferedReader(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) {
					out.write("Yes");
					break;
				}
				a -= d;
				if (a <= 0) {
					out.write("No");
					break;
				}
			}
			out.close();
		}
	}

}