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