import java.util.*;
import java.util.HashSet;
import java.util.Map;
import java.util.HashMap;
import java.util.ArrayList;
import java.util.List;
import java.util.Arrays;
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();

        while (a > 0 || c > 0){
            c -= b;
            if (c <= 0){
                System.out.println("Yes");
                break;
            }
            a -= d;
            if (a <= 0){
                System.out.println("No");
                break;
            }
        }

    }
}



 import java.util.*; util.* java import java.util.HashSet; HashSet java.util import java.util.Map; Map java.util import java.util.HashMap; HashMap java.util import java.util.ArrayList; ArrayList java.util import java.util.List; List java.util import java.util.Arrays; Arrays java.util 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();

        while (a > 0 || c > 0){
            c -= b;
            if (c <= 0){
                System.out.println("Yes");
                break;
            }
            a -= d;
            if (a <= 0){
                System.out.println("No");
                break;
            }
        }

    }
} 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();

        while (a > 0 || c > 0){
            c -= b;
            if (c <= 0){
                System.out.println("Yes");
                break;
            }
            a -= d;
            if (a <= 0){
                System.out.println("No");
                break;
            }
        }

    } 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 > 0){
            c -= b;
            if (c <= 0){
                System.out.println("Yes");
                break;
            }
            a -= d;
            if (a <= 0){
                System.out.println("No");
                break;
            }
        }

    } 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 > 0){
            c -= b;
            if (c <= 0){
                System.out.println("Yes");
                break;
            }
            a -= d;
            if (a <= 0){
                System.out.println("No");
                break;
            }
        } a > 0 || c > 0 a > 0 a 0 c > 0 c 0 {
            c -= b;
            if (c <= 0){
                System.out.println("Yes");
                break;
            }
            a -= d;
            if (a <= 0){
                System.out.println("No");
                break;
            }
        } c -= b c b if (c <= 0){
                System.out.println("Yes");
                break;
            } c <= 0 c 0 {
                System.out.println("Yes");
                break;
            } System.out.println("Yes") System.out.println System.out System System.out "Yes" break; a -= d a d if (a <= 0){
                System.out.println("No");
                break;
            } a <= 0 a 0 {
                System.out.println("No");
                break;
            } System.out.println("No") System.out.println System.out System System.out "No" break; 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();

        while (a > 0 || c > 0){
            c -= b;
            if (c <= 0){
                System.out.println("Yes");
                break;
            }
            a -= d;
            if (a <= 0){
                System.out.println("No");
                break;
            }
        }

    }
} 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();

        while (a > 0 || c > 0){
            c -= b;
            if (c <= 0){
                System.out.println("Yes");
                break;
            }
            a -= d;
            if (a <= 0){
                System.out.println("No");
                break;
            }
        }

    }
} Main
import java.util.*;
import java.util.HashSet;
import java.util.Map;
import java.util.HashMap;
import java.util.ArrayList;
import java.util.List;
import java.util.Arrays;
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();

        while (a > 0 || c > 0){
            c -= b;
            if (c <= 0){
                System.out.println("Yes");
                break;
            }
            a -= d;
            if (a <= 0){
                System.out.println("No");
                break;
            }
        }

    }
}




