import java.util.*;
import java.io.*;
import java.nio.charset.StandardCharsets;

public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		int C = Integer.parseInt(tokens[2]);
		int D = Integer.parseInt(tokens[3]);

		int turnTakahashi = C / B;
		if (C % B > 0) {
			turnTakahashi++;
		}
		int turnAoki = A / D;
		if (A % D > 0) {
			turnAoki++;
		}
		if (turnTakahashi <= turnAoki) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}

	void calc() {
	}

	void showResult() {
	}

} import java.util.*; util.* java import java.io.*; io.* java import java.nio.charset.StandardCharsets; StandardCharsets java.nio.charset public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		int C = Integer.parseInt(tokens[2]);
		int D = Integer.parseInt(tokens[3]);

		int turnTakahashi = C / B;
		if (C % B > 0) {
			turnTakahashi++;
		}
		int turnAoki = A / D;
		if (A % D > 0) {
			turnAoki++;
		}
		if (turnTakahashi <= turnAoki) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}

	void calc() {
	}

	void showResult() {
	}

} Main public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	} main {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	} InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8); reader new InputStreamReader(System.in, StandardCharsets.UTF_8) BufferedReader in = new BufferedReader(reader); in new BufferedReader(reader) Main ins = new Main(in); ins new Main(in) ins.calc() ins.calc ins ins.showResult() ins.showResult ins String[] args args Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		int C = Integer.parseInt(tokens[2]);
		int D = Integer.parseInt(tokens[3]);

		int turnTakahashi = C / B;
		if (C % B > 0) {
			turnTakahashi++;
		}
		int turnAoki = A / D;
		if (A % D > 0) {
			turnAoki++;
		}
		if (turnTakahashi <= turnAoki) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	} Main {
		String[] tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		int C = Integer.parseInt(tokens[2]);
		int D = Integer.parseInt(tokens[3]);

		int turnTakahashi = C / B;
		if (C % B > 0) {
			turnTakahashi++;
		}
		int turnAoki = A / D;
		if (A % D > 0) {
			turnAoki++;
		}
		if (turnTakahashi <= turnAoki) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	} String[] tokens = in.readLine().split(" "); tokens in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " int A = Integer.parseInt(tokens[0]); A Integer.parseInt(tokens[0]) Integer.parseInt Integer tokens[0] tokens 0 int B = Integer.parseInt(tokens[1]); B Integer.parseInt(tokens[1]) Integer.parseInt Integer tokens[1] tokens 1 int C = Integer.parseInt(tokens[2]); C Integer.parseInt(tokens[2]) Integer.parseInt Integer tokens[2] tokens 2 int D = Integer.parseInt(tokens[3]); D Integer.parseInt(tokens[3]) Integer.parseInt Integer tokens[3] tokens 3 int turnTakahashi = C / B; turnTakahashi C / B C B if (C % B > 0) {
			turnTakahashi++;
		} C % B > 0 C % B C B 0 {
			turnTakahashi++;
		} turnTakahashi++ turnTakahashi int turnAoki = A / D; turnAoki A / D A D if (A % D > 0) {
			turnAoki++;
		} A % D > 0 A % D A D 0 {
			turnAoki++;
		} turnAoki++ turnAoki if (turnTakahashi <= turnAoki) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		} turnTakahashi <= turnAoki turnTakahashi turnAoki {
			System.out.println("Yes");
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" {
			System.out.println("No");
		} System.out.println("No") System.out.println System.out System System.out "No" BufferedReader in in void calc() {
	} calc {
	} void showResult() {
	} showResult {
	} public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		int C = Integer.parseInt(tokens[2]);
		int D = Integer.parseInt(tokens[3]);

		int turnTakahashi = C / B;
		if (C % B > 0) {
			turnTakahashi++;
		}
		int turnAoki = A / D;
		if (A % D > 0) {
			turnAoki++;
		}
		if (turnTakahashi <= turnAoki) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}

	void calc() {
	}

	void showResult() {
	}

} public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		int C = Integer.parseInt(tokens[2]);
		int D = Integer.parseInt(tokens[3]);

		int turnTakahashi = C / B;
		if (C % B > 0) {
			turnTakahashi++;
		}
		int turnAoki = A / D;
		if (A % D > 0) {
			turnAoki++;
		}
		if (turnTakahashi <= turnAoki) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}

	void calc() {
	}

	void showResult() {
	}

} Main
import java.util.*;
import java.io.*;
import java.nio.charset.StandardCharsets;

public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		int A = Integer.parseInt(tokens[0]);
		int B = Integer.parseInt(tokens[1]);
		int C = Integer.parseInt(tokens[2]);
		int D = Integer.parseInt(tokens[3]);

		int turnTakahashi = C / B;
		if (C % B > 0) {
			turnTakahashi++;
		}
		int turnAoki = A / D;
		if (A % D > 0) {
			turnAoki++;
		}
		if (turnTakahashi <= turnAoki) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}

	void calc() {
	}

	void showResult() {
	}

}
