import java.util.*;

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 c1 = 0;
      	int c2 = 0;
        while(C > 0){
          C = C - B;
          c1 += 1;
        }
      	while(A > 0){
          A = A - D;
          c2 += 1;
        }
      	if (c2 >= c1)
            System.out.println("Yes");
        else
            System.out.println("No");
    }
} import java.util.*; util.* java 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 c1 = 0;
      	int c2 = 0;
        while(C > 0){
          C = C - B;
          c1 += 1;
        }
      	while(A > 0){
          A = A - D;
          c2 += 1;
        }
      	if (c2 >= c1)
            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 c1 = 0;
      	int c2 = 0;
        while(C > 0){
          C = C - B;
          c1 += 1;
        }
      	while(A > 0){
          A = A - D;
          c2 += 1;
        }
      	if (c2 >= c1)
            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 c1 = 0;
      	int c2 = 0;
        while(C > 0){
          C = C - B;
          c1 += 1;
        }
      	while(A > 0){
          A = A - D;
          c2 += 1;
        }
      	if (c2 >= c1)
            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 c1 = 0; c1 0 int c2 = 0; c2 0 while(C > 0){
          C = C - B;
          c1 += 1;
        } C > 0 C 0 {
          C = C - B;
          c1 += 1;
        } C = C - B C C - B C B c1 += 1 c1 1 while(A > 0){
          A = A - D;
          c2 += 1;
        } A > 0 A 0 {
          A = A - D;
          c2 += 1;
        } A = A - D A A - D A D c2 += 1 c2 1 if (c2 >= c1)
            System.out.println("Yes");
        else
            System.out.println("No"); c2 >= c1 c2 c1 System.out.println("Yes") System.out.println System.out System System.out "Yes" System.out.println("No") System.out.println System.out System System.out "No" String[] args args
import java.util.*;

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 c1 = 0;
      	int c2 = 0;
        while(C > 0){
          C = C - B;
          c1 += 1;
        }
      	while(A > 0){
          A = A - D;
          c2 += 1;
        }
      	if (c2 >= c1)
            System.out.println("Yes");
        else
            System.out.println("No");
    }
}