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