import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int aHP = scanner.nextInt();
        int aPower = scanner.nextInt();
        int bHP = scanner.nextInt();
        int bPower = scanner.nextInt();
        bHP -= aPower;
        while(bHP > 0) {
            aHP -= bPower;
            if (aHP < 1) {
                System.out.println("No");
                return;
            }
            bHP -= aPower;
        }
        System.out.println("Yes");
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int aHP = scanner.nextInt();
        int aPower = scanner.nextInt();
        int bHP = scanner.nextInt();
        int bPower = scanner.nextInt();
        bHP -= aPower;
        while(bHP > 0) {
            aHP -= bPower;
            if (aHP < 1) {
                System.out.println("No");
                return;
            }
            bHP -= aPower;
        }
        System.out.println("Yes");
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int aHP = scanner.nextInt();
        int aPower = scanner.nextInt();
        int bHP = scanner.nextInt();
        int bPower = scanner.nextInt();
        bHP -= aPower;
        while(bHP > 0) {
            aHP -= bPower;
            if (aHP < 1) {
                System.out.println("No");
                return;
            }
            bHP -= aPower;
        }
        System.out.println("Yes");
    } main {
        Scanner scanner = new Scanner(System.in);
        int aHP = scanner.nextInt();
        int aPower = scanner.nextInt();
        int bHP = scanner.nextInt();
        int bPower = scanner.nextInt();
        bHP -= aPower;
        while(bHP > 0) {
            aHP -= bPower;
            if (aHP < 1) {
                System.out.println("No");
                return;
            }
            bHP -= aPower;
        }
        System.out.println("Yes");
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int aHP = scanner.nextInt(); aHP scanner.nextInt() scanner.nextInt scanner int aPower = scanner.nextInt(); aPower scanner.nextInt() scanner.nextInt scanner int bHP = scanner.nextInt(); bHP scanner.nextInt() scanner.nextInt scanner int bPower = scanner.nextInt(); bPower scanner.nextInt() scanner.nextInt scanner bHP -= aPower bHP aPower while(bHP > 0) {
            aHP -= bPower;
            if (aHP < 1) {
                System.out.println("No");
                return;
            }
            bHP -= aPower;
        } bHP > 0 bHP 0 {
            aHP -= bPower;
            if (aHP < 1) {
                System.out.println("No");
                return;
            }
            bHP -= aPower;
        } aHP -= bPower aHP bPower if (aHP < 1) {
                System.out.println("No");
                return;
            } aHP < 1 aHP 1 {
                System.out.println("No");
                return;
            } System.out.println("No") System.out.println System.out System System.out "No" return; bHP -= aPower bHP aPower System.out.println("Yes") System.out.println System.out System System.out "Yes" String[] args args public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int aHP = scanner.nextInt();
        int aPower = scanner.nextInt();
        int bHP = scanner.nextInt();
        int bPower = scanner.nextInt();
        bHP -= aPower;
        while(bHP > 0) {
            aHP -= bPower;
            if (aHP < 1) {
                System.out.println("No");
                return;
            }
            bHP -= aPower;
        }
        System.out.println("Yes");
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int aHP = scanner.nextInt();
        int aPower = scanner.nextInt();
        int bHP = scanner.nextInt();
        int bPower = scanner.nextInt();
        bHP -= aPower;
        while(bHP > 0) {
            aHP -= bPower;
            if (aHP < 1) {
                System.out.println("No");
                return;
            }
            bHP -= aPower;
        }
        System.out.println("Yes");
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int aHP = scanner.nextInt();
        int aPower = scanner.nextInt();
        int bHP = scanner.nextInt();
        int bPower = scanner.nextInt();
        bHP -= aPower;
        while(bHP > 0) {
            aHP -= bPower;
            if (aHP < 1) {
                System.out.println("No");
                return;
            }
            bHP -= aPower;
        }
        System.out.println("Yes");
    }
}