import sys

def input(): return sys.stdin.readline().rstrip()



def main():

    A, B, C, D = list(map(int, input().split()))

    while True:

        C -= B

        if C <= 0:

            print('Yes')

            exit()

        A -= D

        if A <= 0:

            print('No')

            exit()



if __name__ == '__main__':

    main()

import sys

def input(): return sys.stdin.readline().rstrip()



def main():

    A, B, C, D = list(map(int, input().split()))

    A_dead = (A + D - 1) // D

    C_dead = (C + B - 1) // B

    if A_dead >= C_dead:

        print('Yes')

    else:

        print('No')



if __name__ == '__main__':

    main()

import sys


def input():
    return sys.stdin.readline().rstrip()


def main():
    A, B, C, D = list(map(int, input().split()))
    while True:
        C -= B
        if C <= 0:
            print("Yes")
            exit()
        A -= D
        if A <= 0:
            print("No")
            exit()


if __name__ == "__main__":
    main()

import sys


def input():
    return sys.stdin.readline().rstrip()


def main():
    A, B, C, D = list(map(int, input().split()))
    A_dead = (A + D - 1) // D
    C_dead = (C + B - 1) // B
    if A_dead >= C_dead:
        print("Yes")
    else:
        print("No")


if __name__ == "__main__":
    main()

-    while True: -        C -= B -        if C <= 0: -            print("Yes") -            exit() -        A -= D -        if A <= 0: -            print("No") -            exit() +    A_dead = (A + D - 1) // D +    C_dead = (C + B - 1) // B +    if A_dead >= C_dead: +        print("Yes") +    else: +        print("No")