import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		boolean flg = false;
//		高橋体力
		int A = sc.nextInt();
//		高橋攻撃力
		int B = sc.nextInt();
//		青木体力
		int C = sc.nextInt();
//		青木攻撃力
		int D = sc.nextInt();
		while(true) {
			C = C - B;
			if(C <= 0) {
				break;
			}
			A = A - D;			
			if(A <= 0) {
				flg = true;
				break;
			}
		}
		if(flg) {
			System.out.println("No");						
		}else {
			System.out.println("Yes");									
		}
	}
} import java.util.Scanner; Scanner java.util import java.util.ArrayList; ArrayList java.util import java.util.List; List java.util public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		boolean flg = false;
//		高橋体力
		int A = sc.nextInt();
//		高橋攻撃力
		int B = sc.nextInt();
//		青木体力
		int C = sc.nextInt();
//		青木攻撃力
		int D = sc.nextInt();
		while(true) {
			C = C - B;
			if(C <= 0) {
				break;
			}
			A = A - D;			
			if(A <= 0) {
				flg = true;
				break;
			}
		}
		if(flg) {
			System.out.println("No");						
		}else {
			System.out.println("Yes");									
		}
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		boolean flg = false;
//		高橋体力
		int A = sc.nextInt();
//		高橋攻撃力
		int B = sc.nextInt();
//		青木体力
		int C = sc.nextInt();
//		青木攻撃力
		int D = sc.nextInt();
		while(true) {
			C = C - B;
			if(C <= 0) {
				break;
			}
			A = A - D;			
			if(A <= 0) {
				flg = true;
				break;
			}
		}
		if(flg) {
			System.out.println("No");						
		}else {
			System.out.println("Yes");									
		}
	} main {
		Scanner sc = new Scanner(System.in);
		boolean flg = false;
//		高橋体力
		int A = sc.nextInt();
//		高橋攻撃力
		int B = sc.nextInt();
//		青木体力
		int C = sc.nextInt();
//		青木攻撃力
		int D = sc.nextInt();
		while(true) {
			C = C - B;
			if(C <= 0) {
				break;
			}
			A = A - D;			
			if(A <= 0) {
				flg = true;
				break;
			}
		}
		if(flg) {
			System.out.println("No");						
		}else {
			System.out.println("Yes");									
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) boolean flg = false; flg false int A = sc.nextInt(); A sc.nextInt() sc.nextInt sc int B = sc.nextInt(); B sc.nextInt() sc.nextInt sc int C = sc.nextInt(); C sc.nextInt() sc.nextInt sc int D = sc.nextInt(); D sc.nextInt() sc.nextInt sc while(true) {
			C = C - B;
			if(C <= 0) {
				break;
			}
			A = A - D;			
			if(A <= 0) {
				flg = true;
				break;
			}
		} true {
			C = C - B;
			if(C <= 0) {
				break;
			}
			A = A - D;			
			if(A <= 0) {
				flg = true;
				break;
			}
		} C = C - B C C - B C B if(C <= 0) {
				break;
			} C <= 0 C 0 {
				break;
			} break; A = A - D A A - D A D if(A <= 0) {
				flg = true;
				break;
			} A <= 0 A 0 {
				flg = true;
				break;
			} flg = true flg true break; if(flg) {
			System.out.println("No");						
		}else {
			System.out.println("Yes");									
		} flg {
			System.out.println("No");						
		} System.out.println("No") System.out.println System.out System System.out "No" {
			System.out.println("Yes");									
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		boolean flg = false;
//		高橋体力
		int A = sc.nextInt();
//		高橋攻撃力
		int B = sc.nextInt();
//		青木体力
		int C = sc.nextInt();
//		青木攻撃力
		int D = sc.nextInt();
		while(true) {
			C = C - B;
			if(C <= 0) {
				break;
			}
			A = A - D;			
			if(A <= 0) {
				flg = true;
				break;
			}
		}
		if(flg) {
			System.out.println("No");						
		}else {
			System.out.println("Yes");									
		}
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		boolean flg = false;
//		高橋体力
		int A = sc.nextInt();
//		高橋攻撃力
		int B = sc.nextInt();
//		青木体力
		int C = sc.nextInt();
//		青木攻撃力
		int D = sc.nextInt();
		while(true) {
			C = C - B;
			if(C <= 0) {
				break;
			}
			A = A - D;			
			if(A <= 0) {
				flg = true;
				break;
			}
		}
		if(flg) {
			System.out.println("No");						
		}else {
			System.out.println("Yes");									
		}
	}
} Main
import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		boolean flg = false;
//		高橋体力
		int A = sc.nextInt();
//		高橋攻撃力
		int B = sc.nextInt();
//		青木体力
		int C = sc.nextInt();
//		青木攻撃力
		int D = sc.nextInt();
		while(true) {
			C = C - B;
			if(C <= 0) {
				break;
			}
			A = A - D;			
			if(A <= 0) {
				flg = true;
				break;
			}
		}
		if(flg) {
			System.out.println("No");						
		}else {
			System.out.println("Yes");									
		}
	}
}