import java.util.*;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		int flag = 0;
		
		while(true){
			C = C - B;
			if (C <= 0){
				break;
			}
			A = A - D;
			if (A <= 0){
				flag = 1;
				break;
			}
		}
		
		if (flag == 0){
			System.out.println("Yes");
		}
		else{
			System.out.println("No");
		}
	}
} import java.util.*; util.* java public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		int flag = 0;
		
		while(true){
			C = C - B;
			if (C <= 0){
				break;
			}
			A = A - D;
			if (A <= 0){
				flag = 1;
				break;
			}
		}
		
		if (flag == 0){
			System.out.println("Yes");
		}
		else{
			System.out.println("No");
		}
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		int flag = 0;
		
		while(true){
			C = C - B;
			if (C <= 0){
				break;
			}
			A = A - D;
			if (A <= 0){
				flag = 1;
				break;
			}
		}
		
		if (flag == 0){
			System.out.println("Yes");
		}
		else{
			System.out.println("No");
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		int flag = 0;
		
		while(true){
			C = C - B;
			if (C <= 0){
				break;
			}
			A = A - D;
			if (A <= 0){
				flag = 1;
				break;
			}
		}
		
		if (flag == 0){
			System.out.println("Yes");
		}
		else{
			System.out.println("No");
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) 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 int flag = 0; flag 0 while(true){
			C = C - B;
			if (C <= 0){
				break;
			}
			A = A - D;
			if (A <= 0){
				flag = 1;
				break;
			}
		} true {
			C = C - B;
			if (C <= 0){
				break;
			}
			A = A - D;
			if (A <= 0){
				flag = 1;
				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){
				flag = 1;
				break;
			} A <= 0 A 0 {
				flag = 1;
				break;
			} flag = 1 flag 1 break; if (flag == 0){
			System.out.println("Yes");
		}
		else{
			System.out.println("No");
		} flag == 0 flag 0 {
			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" String[] args args public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		int flag = 0;
		
		while(true){
			C = C - B;
			if (C <= 0){
				break;
			}
			A = A - D;
			if (A <= 0){
				flag = 1;
				break;
			}
		}
		
		if (flag == 0){
			System.out.println("Yes");
		}
		else{
			System.out.println("No");
		}
	}
} public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		int flag = 0;
		
		while(true){
			C = C - B;
			if (C <= 0){
				break;
			}
			A = A - D;
			if (A <= 0){
				flag = 1;
				break;
			}
		}
		
		if (flag == 0){
			System.out.println("Yes");
		}
		else{
			System.out.println("No");
		}
	}
} Main
import java.util.*;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int C = sc.nextInt();
		int D = sc.nextInt();
		int flag = 0;
		
		while(true){
			C = C - B;
			if (C <= 0){
				break;
			}
			A = A - D;
			if (A <= 0){
				flag = 1;
				break;
			}
		}
		
		if (flag == 0){
			System.out.println("Yes");
		}
		else{
			System.out.println("No");
		}
	}
}
