import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt(), b = sc.nextInt(), c = sc.nextInt(), d = sc.nextInt();
        int x = (int)Math.ceil((double)c / b);
        System.out.println(d * (x - 1) < a ? "Yes" : "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(), b = sc.nextInt(), c = sc.nextInt(), d = sc.nextInt();
        int x = (int)Math.ceil((double)c / b);
        System.out.println(d * (x - 1) < a ? "Yes" : "No");
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt(), b = sc.nextInt(), c = sc.nextInt(), d = sc.nextInt();
        int x = (int)Math.ceil((double)c / b);
        System.out.println(d * (x - 1) < a ? "Yes" : "No");
    } main {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt(), b = sc.nextInt(), c = sc.nextInt(), d = sc.nextInt();
        int x = (int)Math.ceil((double)c / b);
        System.out.println(d * (x - 1) < a ? "Yes" : "No");
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt() a sc.nextInt() sc.nextInt sc b = sc.nextInt() b sc.nextInt() sc.nextInt sc c = sc.nextInt() c sc.nextInt() sc.nextInt sc d = sc.nextInt(); d sc.nextInt() sc.nextInt sc int x = (int)Math.ceil((double)c / b); x (int)Math.ceil((double)c / b) Math.ceil Math (double)c / b (double)c b System.out.println(d * (x - 1) < a ? "Yes" : "No") System.out.println System.out System System.out d * (x - 1) < a ? "Yes" : "No" d * (x - 1) < a d * (x - 1) d (x - 1) x 1 a "Yes" "No" String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt(), b = sc.nextInt(), c = sc.nextInt(), d = sc.nextInt();
        int x = (int)Math.ceil((double)c / b);
        System.out.println(d * (x - 1) < a ? "Yes" : "No");
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt(), b = sc.nextInt(), c = sc.nextInt(), d = sc.nextInt();
        int x = (int)Math.ceil((double)c / b);
        System.out.println(d * (x - 1) < a ? "Yes" : "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(), b = sc.nextInt(), c = sc.nextInt(), d = sc.nextInt();
        int x = (int)Math.ceil((double)c / b);
        System.out.println(d * (x - 1) < a ? "Yes" : "No");
    }
}
