import java.util.Scanner;
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 counta = 0;
        while(C-B>0){
            C -= B;
                counta++;
        }
        int countt = 0;
        while(A-D>0){
            A -= D;
                countt++;
        }
        if(counta<=countt){
        System.out.println("Yes");
        }else{
        System.out.println("No");            
        }
	}
} import java.util.Scanner; Scanner 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 counta = 0;
        while(C-B>0){
            C -= B;
                counta++;
        }
        int countt = 0;
        while(A-D>0){
            A -= D;
                countt++;
        }
        if(counta<=countt){
        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 counta = 0;
        while(C-B>0){
            C -= B;
                counta++;
        }
        int countt = 0;
        while(A-D>0){
            A -= D;
                countt++;
        }
        if(counta<=countt){
        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 counta = 0;
        while(C-B>0){
            C -= B;
                counta++;
        }
        int countt = 0;
        while(A-D>0){
            A -= D;
                countt++;
        }
        if(counta<=countt){
        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 counta = 0; counta 0 while(C-B>0){
            C -= B;
                counta++;
        } C-B>0 C-B C B 0 {
            C -= B;
                counta++;
        } C -= B C B counta++ counta int countt = 0; countt 0 while(A-D>0){
            A -= D;
                countt++;
        } A-D>0 A-D A D 0 {
            A -= D;
                countt++;
        } A -= D A D countt++ countt if(counta<=countt){
        System.out.println("Yes");
        }else{
        System.out.println("No");            
        } counta<=countt counta countt {
        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 counta = 0;
        while(C-B>0){
            C -= B;
                counta++;
        }
        int countt = 0;
        while(A-D>0){
            A -= D;
                countt++;
        }
        if(counta<=countt){
        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 counta = 0;
        while(C-B>0){
            C -= B;
                counta++;
        }
        int countt = 0;
        while(A-D>0){
            A -= D;
                countt++;
        }
        if(counta<=countt){
        System.out.println("Yes");
        }else{
        System.out.println("No");            
        }
	}
} Main
import java.util.Scanner;
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 counta = 0;
        while(C-B>0){
            C -= B;
                counta++;
        }
        int countt = 0;
        while(A-D>0){
            A -= D;
                countt++;
        }
        if(counta<=countt){
        System.out.println("Yes");
        }else{
        System.out.println("No");            
        }
	}
}