import java.io.*;

public class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader reader =
            new BufferedReader (new InputStreamReader (System.in));
        String[] arr = reader.readLine().split (" ");
        int A, B, C, D;
        A = Integer.parseInt (arr[0]);
        B = Integer.parseInt (arr[1]);
        C = Integer.parseInt (arr[2]);
        D = Integer.parseInt (arr[3]);
        System.out.println ((B + C - 1) / B <= (A + D - 1) / D ? "Yes" : "No");
        return;
    }
} import java.io.*; io.* java public class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader reader =
            new BufferedReader (new InputStreamReader (System.in));
        String[] arr = reader.readLine().split (" ");
        int A, B, C, D;
        A = Integer.parseInt (arr[0]);
        B = Integer.parseInt (arr[1]);
        C = Integer.parseInt (arr[2]);
        D = Integer.parseInt (arr[3]);
        System.out.println ((B + C - 1) / B <= (A + D - 1) / D ? "Yes" : "No");
        return;
    }
} Main public static void main (String[] args) throws Exception {
        BufferedReader reader =
            new BufferedReader (new InputStreamReader (System.in));
        String[] arr = reader.readLine().split (" ");
        int A, B, C, D;
        A = Integer.parseInt (arr[0]);
        B = Integer.parseInt (arr[1]);
        C = Integer.parseInt (arr[2]);
        D = Integer.parseInt (arr[3]);
        System.out.println ((B + C - 1) / B <= (A + D - 1) / D ? "Yes" : "No");
        return;
    } main {
        BufferedReader reader =
            new BufferedReader (new InputStreamReader (System.in));
        String[] arr = reader.readLine().split (" ");
        int A, B, C, D;
        A = Integer.parseInt (arr[0]);
        B = Integer.parseInt (arr[1]);
        C = Integer.parseInt (arr[2]);
        D = Integer.parseInt (arr[3]);
        System.out.println ((B + C - 1) / B <= (A + D - 1) / D ? "Yes" : "No");
        return;
    } BufferedReader reader =
            new BufferedReader (new InputStreamReader (System.in)); reader new BufferedReader (new InputStreamReader (System.in)) String[] arr = reader.readLine().split (" "); arr reader.readLine().split (" ") reader.readLine().split reader.readLine() reader.readLine reader " " int A A B B C C D; D A = Integer.parseInt (arr[0]) A Integer.parseInt (arr[0]) Integer.parseInt Integer arr[0] arr 0 B = Integer.parseInt (arr[1]) B Integer.parseInt (arr[1]) Integer.parseInt Integer arr[1] arr 1 C = Integer.parseInt (arr[2]) C Integer.parseInt (arr[2]) Integer.parseInt Integer arr[2] arr 2 D = Integer.parseInt (arr[3]) D Integer.parseInt (arr[3]) Integer.parseInt Integer arr[3] arr 3 System.out.println ((B + C - 1) / B <= (A + D - 1) / D ? "Yes" : "No") System.out.println System.out System System.out (B + C - 1) / B <= (A + D - 1) / D ? "Yes" : "No" (B + C - 1) / B <= (A + D - 1) / D (B + C - 1) / B (B + C - 1) B + C B C 1 B (A + D - 1) / D (A + D - 1) A + D A D 1 D "Yes" "No" return; String[] args args public class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader reader =
            new BufferedReader (new InputStreamReader (System.in));
        String[] arr = reader.readLine().split (" ");
        int A, B, C, D;
        A = Integer.parseInt (arr[0]);
        B = Integer.parseInt (arr[1]);
        C = Integer.parseInt (arr[2]);
        D = Integer.parseInt (arr[3]);
        System.out.println ((B + C - 1) / B <= (A + D - 1) / D ? "Yes" : "No");
        return;
    }
} public class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader reader =
            new BufferedReader (new InputStreamReader (System.in));
        String[] arr = reader.readLine().split (" ");
        int A, B, C, D;
        A = Integer.parseInt (arr[0]);
        B = Integer.parseInt (arr[1]);
        C = Integer.parseInt (arr[2]);
        D = Integer.parseInt (arr[3]);
        System.out.println ((B + C - 1) / B <= (A + D - 1) / D ? "Yes" : "No");
        return;
    }
} Main
import java.io.*;

public class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader reader =
            new BufferedReader (new InputStreamReader (System.in));
        String[] arr = reader.readLine().split (" ");
        int A, B, C, D;
        A = Integer.parseInt (arr[0]);
        B = Integer.parseInt (arr[1]);
        C = Integer.parseInt (arr[2]);
        D = Integer.parseInt (arr[3]);
        System.out.println ((B + C - 1) / B <= (A + D - 1) / D ? "Yes" : "No");
        return;
    }
}