import java.util.*;
public class Main{
	public static void main(String[] args){
      Scanner i = new Scanner(System.in);
      int A = i.nextInt();
      int B = i.nextInt();
      int C = i.nextInt();
      int D = i.nextInt();
      boolean ta = false;
      for(int j=1;true;j++){
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      }
      System.out.println(ta?"Yes":"No");
    }
} import java.util.*; util.* java public class Main{
	public static void main(String[] args){
      Scanner i = new Scanner(System.in);
      int A = i.nextInt();
      int B = i.nextInt();
      int C = i.nextInt();
      int D = i.nextInt();
      boolean ta = false;
      for(int j=1;true;j++){
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      }
      System.out.println(ta?"Yes":"No");
    }
} Main public static void main(String[] args){
      Scanner i = new Scanner(System.in);
      int A = i.nextInt();
      int B = i.nextInt();
      int C = i.nextInt();
      int D = i.nextInt();
      boolean ta = false;
      for(int j=1;true;j++){
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      }
      System.out.println(ta?"Yes":"No");
    } main {
      Scanner i = new Scanner(System.in);
      int A = i.nextInt();
      int B = i.nextInt();
      int C = i.nextInt();
      int D = i.nextInt();
      boolean ta = false;
      for(int j=1;true;j++){
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      }
      System.out.println(ta?"Yes":"No");
    } Scanner i = new Scanner(System.in); i new Scanner(System.in) int A = i.nextInt(); A i.nextInt() i.nextInt i int B = i.nextInt(); B i.nextInt() i.nextInt i int C = i.nextInt(); C i.nextInt() i.nextInt i int D = i.nextInt(); D i.nextInt() i.nextInt i boolean ta = false; ta false for(int j=1;true;j++){
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      } int j=1; int j=1; j 1 true j++ j++ j {
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      } {
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      } C-=B C B if(C<=0){ta=true;break;} C<=0 C 0 {ta=true;break;} ta=true ta true break; A-=D A D if(A<=0){ta=false;break;} A<=0 A 0 {ta=false;break;} ta=false ta false break; System.out.println(ta?"Yes":"No") System.out.println System.out System System.out ta?"Yes":"No" ta "Yes" "No" String[] args args public class Main{
	public static void main(String[] args){
      Scanner i = new Scanner(System.in);
      int A = i.nextInt();
      int B = i.nextInt();
      int C = i.nextInt();
      int D = i.nextInt();
      boolean ta = false;
      for(int j=1;true;j++){
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      }
      System.out.println(ta?"Yes":"No");
    }
} public class Main{
	public static void main(String[] args){
      Scanner i = new Scanner(System.in);
      int A = i.nextInt();
      int B = i.nextInt();
      int C = i.nextInt();
      int D = i.nextInt();
      boolean ta = false;
      for(int j=1;true;j++){
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      }
      System.out.println(ta?"Yes":"No");
    }
} Main
import java.util.*;
public class Main{
	public static void main(String[] args){
      Scanner i = new Scanner(System.in);
      int A = i.nextInt();
      int B = i.nextInt();
      int C = i.nextInt();
      int D = i.nextInt();
      boolean ta = false;
      for(int j=1;true;j++){
      	C-=B;
        if(C<=0){ta=true;break;}
        A-=D;
        if(A<=0){ta=false;break;}
      }
      System.out.println(ta?"Yes":"No");
    }
}