import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int A = sc.nextInt();
      	int B = sc.nextInt();
      	int C = sc.nextInt();
      	int D = sc.nextInt();
      	
       	boolean flg=true;
      	for(;flg==true;){
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         }
        
		
		
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int A = sc.nextInt();
      	int B = sc.nextInt();
      	int C = sc.nextInt();
      	int D = sc.nextInt();
      	
       	boolean flg=true;
      	for(;flg==true;){
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         }
        
		
		
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int A = sc.nextInt();
      	int B = sc.nextInt();
      	int C = sc.nextInt();
      	int D = sc.nextInt();
      	
       	boolean flg=true;
      	for(;flg==true;){
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         }
        
		
		
	} main {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int A = sc.nextInt();
      	int B = sc.nextInt();
      	int C = sc.nextInt();
      	int D = sc.nextInt();
      	
       	boolean flg=true;
      	for(;flg==true;){
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         }
        
		
		
	} 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 boolean flg=true; flg true for(;flg==true;){
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         } ; flg==true flg true {
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         } {
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         } C=C-B C C-B C B if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         } C<=0 C 0 {
         System.out.println("Yes");
         flg=false;
           break;
         } System.out.println("Yes") System.out.println System.out System System.out "Yes" flg=false flg false break; A=A-D A A-D A D if(A<=0){
         System.out.println("No");
         flg=false;
         } A<=0 A 0 {
         System.out.println("No");
         flg=false;
         } System.out.println("No") System.out.println System.out System System.out "No" flg=false flg false String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int A = sc.nextInt();
      	int B = sc.nextInt();
      	int C = sc.nextInt();
      	int D = sc.nextInt();
      	
       	boolean flg=true;
      	for(;flg==true;){
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         }
        
		
		
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int A = sc.nextInt();
      	int B = sc.nextInt();
      	int C = sc.nextInt();
      	int D = sc.nextInt();
      	
       	boolean flg=true;
      	for(;flg==true;){
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         }
        
		
		
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int A = sc.nextInt();
      	int B = sc.nextInt();
      	int C = sc.nextInt();
      	int D = sc.nextInt();
      	
       	boolean flg=true;
      	for(;flg==true;){
          C=C-B;
         if(C<=0){
         System.out.println("Yes");
         flg=false;
           break;
         }
          A=A-D;
          if(A<=0){
         System.out.println("No");
         flg=false;
         }
         }
        
		
		
	}
}