import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();

        while (a > 0) {
            c -= b;

            if (c <= 0) {
                System.out.println("Yes");
                return;
            }
            a -= d;
        }

        System.out.println("No");
    }
} import java.io.File; File java.io import java.io.FileInputStream; FileInputStream java.io import java.io.FileNotFoundException; FileNotFoundException java.io import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();

        while (a > 0) {
            c -= b;

            if (c <= 0) {
                System.out.println("Yes");
                return;
            }
            a -= d;
        }

        System.out.println("No");
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();

        while (a > 0) {
            c -= b;

            if (c <= 0) {
                System.out.println("Yes");
                return;
            }
            a -= d;
        }

        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();

        while (a > 0) {
            c -= b;

            if (c <= 0) {
                System.out.println("Yes");
                return;
            }
            a -= d;
        }

        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 while (a > 0) {
            c -= b;

            if (c <= 0) {
                System.out.println("Yes");
                return;
            }
            a -= d;
        } a > 0 a 0 {
            c -= b;

            if (c <= 0) {
                System.out.println("Yes");
                return;
            }
            a -= d;
        } c -= b c b if (c <= 0) {
                System.out.println("Yes");
                return;
            } c <= 0 c 0 {
                System.out.println("Yes");
                return;
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" return; a -= d a d 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) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();

        while (a > 0) {
            c -= b;

            if (c <= 0) {
                System.out.println("Yes");
                return;
            }
            a -= d;
        }

        System.out.println("No");
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();

        while (a > 0) {
            c -= b;

            if (c <= 0) {
                System.out.println("Yes");
                return;
            }
            a -= d;
        }

        System.out.println("No");
    }
} Main
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();

        while (a > 0) {
            c -= b;

            if (c <= 0) {
                System.out.println("Yes");
                return;
            }
            a -= d;
        }

        System.out.println("No");
    }
}
