import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.nextLine();
		int HT = Integer.valueOf(s.split(" ")[0]);
		int ST = Integer.valueOf(s.split(" ")[1]);
		int HA = Integer.valueOf(s.split(" ")[2]);
		int SA = Integer.valueOf(s.split(" ")[3]);
	
		while(HA > 0 && HT > 0) {
			HA = HA - ST;
			if(HA <= 0)
				break;
			HT = HT - SA;
			if(HT <= 0)
				break;
		}
		//System.out.println(HA + " " + HT);
		
		if(HT > HA) {
			System.out.println("Yes");
		}
		else
			System.out.println("No");
	}

}

class FastReader {
	BufferedReader bf;
	StringTokenizer st;

	public FastReader() {
		bf = new BufferedReader(new InputStreamReader(System.in));
	}

	String next() {
		while (st == null || !st.hasMoreElements()) {
			try {
				st = new StringTokenizer(bf.readLine());
			} catch (Exception e) {
				System.out.println(e);
			}
		}
		return st.nextToken();
	}

	int nextInt() {
		return Integer.parseInt(next());
	}

	long nextLong() {
		return Long.parseLong(next());
	}

	double nextDouble() {
		return Double.parseDouble(next());
	}

	String nextLine() {
		String str = "";
		try {
			str = bf.readLine();
		} catch (Exception e) {
			System.out.println(e);
		}
		return str;
	}
}
 import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.Scanner; Scanner java.util import java.util.StringTokenizer; StringTokenizer java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.nextLine();
		int HT = Integer.valueOf(s.split(" ")[0]);
		int ST = Integer.valueOf(s.split(" ")[1]);
		int HA = Integer.valueOf(s.split(" ")[2]);
		int SA = Integer.valueOf(s.split(" ")[3]);
	
		while(HA > 0 && HT > 0) {
			HA = HA - ST;
			if(HA <= 0)
				break;
			HT = HT - SA;
			if(HT <= 0)
				break;
		}
		//System.out.println(HA + " " + HT);
		
		if(HT > HA) {
			System.out.println("Yes");
		}
		else
			System.out.println("No");
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.nextLine();
		int HT = Integer.valueOf(s.split(" ")[0]);
		int ST = Integer.valueOf(s.split(" ")[1]);
		int HA = Integer.valueOf(s.split(" ")[2]);
		int SA = Integer.valueOf(s.split(" ")[3]);
	
		while(HA > 0 && HT > 0) {
			HA = HA - ST;
			if(HA <= 0)
				break;
			HT = HT - SA;
			if(HT <= 0)
				break;
		}
		//System.out.println(HA + " " + HT);
		
		if(HT > HA) {
			System.out.println("Yes");
		}
		else
			System.out.println("No");
	} main {
		Scanner sc = new Scanner(System.in);
		String s = sc.nextLine();
		int HT = Integer.valueOf(s.split(" ")[0]);
		int ST = Integer.valueOf(s.split(" ")[1]);
		int HA = Integer.valueOf(s.split(" ")[2]);
		int SA = Integer.valueOf(s.split(" ")[3]);
	
		while(HA > 0 && HT > 0) {
			HA = HA - ST;
			if(HA <= 0)
				break;
			HT = HT - SA;
			if(HT <= 0)
				break;
		}
		//System.out.println(HA + " " + HT);
		
		if(HT > HA) {
			System.out.println("Yes");
		}
		else
			System.out.println("No");
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String s = sc.nextLine(); s sc.nextLine() sc.nextLine sc int HT = Integer.valueOf(s.split(" ")[0]); HT Integer.valueOf(s.split(" ")[0]) Integer.valueOf Integer s.split(" ")[0] s.split(" ") s.split s " " 0 int ST = Integer.valueOf(s.split(" ")[1]); ST Integer.valueOf(s.split(" ")[1]) Integer.valueOf Integer s.split(" ")[1] s.split(" ") s.split s " " 1 int HA = Integer.valueOf(s.split(" ")[2]); HA Integer.valueOf(s.split(" ")[2]) Integer.valueOf Integer s.split(" ")[2] s.split(" ") s.split s " " 2 int SA = Integer.valueOf(s.split(" ")[3]); SA Integer.valueOf(s.split(" ")[3]) Integer.valueOf Integer s.split(" ")[3] s.split(" ") s.split s " " 3 while(HA > 0 && HT > 0) {
			HA = HA - ST;
			if(HA <= 0)
				break;
			HT = HT - SA;
			if(HT <= 0)
				break;
		} HA > 0 && HT > 0 HA > 0 HA 0 HT > 0 HT 0 {
			HA = HA - ST;
			if(HA <= 0)
				break;
			HT = HT - SA;
			if(HT <= 0)
				break;
		} HA = HA - ST HA HA - ST HA ST if(HA <= 0)
				break; HA <= 0 HA 0 break; HT = HT - SA HT HT - SA HT SA if(HT <= 0)
				break; HT <= 0 HT 0 break; if(HT > HA) {
			System.out.println("Yes");
		}
		else
			System.out.println("No"); HT > HA HT HA {
			System.out.println("Yes");
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" System.out.println("No") System.out.println System.out System System.out "No" String[] args args class FastReader {
	BufferedReader bf;
	StringTokenizer st;

	public FastReader() {
		bf = new BufferedReader(new InputStreamReader(System.in));
	}

	String next() {
		while (st == null || !st.hasMoreElements()) {
			try {
				st = new StringTokenizer(bf.readLine());
			} catch (Exception e) {
				System.out.println(e);
			}
		}
		return st.nextToken();
	}

	int nextInt() {
		return Integer.parseInt(next());
	}

	long nextLong() {
		return Long.parseLong(next());
	}

	double nextDouble() {
		return Double.parseDouble(next());
	}

	String nextLine() {
		String str = "";
		try {
			str = bf.readLine();
		} catch (Exception e) {
			System.out.println(e);
		}
		return str;
	}
} FastReader BufferedReader bf; bf StringTokenizer st; st public FastReader() {
		bf = new BufferedReader(new InputStreamReader(System.in));
	} FastReader {
		bf = new BufferedReader(new InputStreamReader(System.in));
	} bf = new BufferedReader(new InputStreamReader(System.in)) bf new BufferedReader(new InputStreamReader(System.in)) String next() {
		while (st == null || !st.hasMoreElements()) {
			try {
				st = new StringTokenizer(bf.readLine());
			} catch (Exception e) {
				System.out.println(e);
			}
		}
		return st.nextToken();
	} next {
		while (st == null || !st.hasMoreElements()) {
			try {
				st = new StringTokenizer(bf.readLine());
			} catch (Exception e) {
				System.out.println(e);
			}
		}
		return st.nextToken();
	} while (st == null || !st.hasMoreElements()) {
			try {
				st = new StringTokenizer(bf.readLine());
			} catch (Exception e) {
				System.out.println(e);
			}
		} st == null || !st.hasMoreElements() st == null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
			try {
				st = new StringTokenizer(bf.readLine());
			} catch (Exception e) {
				System.out.println(e);
			}
		} try {
				st = new StringTokenizer(bf.readLine());
			} catch (Exception e) {
				System.out.println(e);
			} catch (Exception e) {
				System.out.println(e);
			} Exception e {
				System.out.println(e);
			} System.out.println(e) System.out.println System.out System System.out e {
				st = new StringTokenizer(bf.readLine());
			} st = new StringTokenizer(bf.readLine()) st new StringTokenizer(bf.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt() {
		return Integer.parseInt(next());
	} nextInt {
		return Integer.parseInt(next());
	} return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() {
		return Long.parseLong(next());
	} nextLong {
		return Long.parseLong(next());
	} return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble() {
		return Double.parseDouble(next());
	} nextDouble {
		return Double.parseDouble(next());
	} return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine() {
		String str = "";
		try {
			str = bf.readLine();
		} catch (Exception e) {
			System.out.println(e);
		}
		return str;
	} nextLine {
		String str = "";
		try {
			str = bf.readLine();
		} catch (Exception e) {
			System.out.println(e);
		}
		return str;
	} String str = ""; str "" try {
			str = bf.readLine();
		} catch (Exception e) {
			System.out.println(e);
		} catch (Exception e) {
			System.out.println(e);
		} Exception e {
			System.out.println(e);
		} System.out.println(e) System.out.println System.out System System.out e {
			str = bf.readLine();
		} str = bf.readLine() str bf.readLine() bf.readLine bf return str; str public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.nextLine();
		int HT = Integer.valueOf(s.split(" ")[0]);
		int ST = Integer.valueOf(s.split(" ")[1]);
		int HA = Integer.valueOf(s.split(" ")[2]);
		int SA = Integer.valueOf(s.split(" ")[3]);
	
		while(HA > 0 && HT > 0) {
			HA = HA - ST;
			if(HA <= 0)
				break;
			HT = HT - SA;
			if(HT <= 0)
				break;
		}
		//System.out.println(HA + " " + HT);
		
		if(HT > HA) {
			System.out.println("Yes");
		}
		else
			System.out.println("No");
	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.nextLine();
		int HT = Integer.valueOf(s.split(" ")[0]);
		int ST = Integer.valueOf(s.split(" ")[1]);
		int HA = Integer.valueOf(s.split(" ")[2]);
		int SA = Integer.valueOf(s.split(" ")[3]);
	
		while(HA > 0 && HT > 0) {
			HA = HA - ST;
			if(HA <= 0)
				break;
			HT = HT - SA;
			if(HT <= 0)
				break;
		}
		//System.out.println(HA + " " + HT);
		
		if(HT > HA) {
			System.out.println("Yes");
		}
		else
			System.out.println("No");
	}

} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.nextLine();
		int HT = Integer.valueOf(s.split(" ")[0]);
		int ST = Integer.valueOf(s.split(" ")[1]);
		int HA = Integer.valueOf(s.split(" ")[2]);
		int SA = Integer.valueOf(s.split(" ")[3]);
	
		while(HA > 0 && HT > 0) {
			HA = HA - ST;
			if(HA <= 0)
				break;
			HT = HT - SA;
			if(HT <= 0)
				break;
		}
		//System.out.println(HA + " " + HT);
		
		if(HT > HA) {
			System.out.println("Yes");
		}
		else
			System.out.println("No");
	}

}

class FastReader {
	BufferedReader bf;
	StringTokenizer st;

	public FastReader() {
		bf = new BufferedReader(new InputStreamReader(System.in));
	}

	String next() {
		while (st == null || !st.hasMoreElements()) {
			try {
				st = new StringTokenizer(bf.readLine());
			} catch (Exception e) {
				System.out.println(e);
			}
		}
		return st.nextToken();
	}

	int nextInt() {
		return Integer.parseInt(next());
	}

	long nextLong() {
		return Long.parseLong(next());
	}

	double nextDouble() {
		return Double.parseDouble(next());
	}

	String nextLine() {
		String str = "";
		try {
			str = bf.readLine();
		} catch (Exception e) {
			System.out.println(e);
		}
		return str;
	}
}

