import sys

input = sys.stdin.readline



a, b, c, d = [int(x) for x in input().split()]



while True:

    for i in range(2):

        if i == 0:

            c -= b

            if c <= 0:

                print("Yes")

                sys.exit()

        else:

            a -= d

            if a <= 0:

                print("No")

                sys.exit()
a, b, c, d = [int(x) for x in input().split()]



while True:

    c -= b

    if c <= 0:

        print("Yes")

        exit()

    a -= d

    if a <= 0:

        print("No")

        exit()

import sys

input = sys.stdin.readline
a, b, c, d = [int(x) for x in input().split()]
while True:
    for i in range(2):
        if i == 0:
            c -= b
            if c <= 0:
                print("Yes")
                sys.exit()
        else:
            a -= d
            if a <= 0:
                print("No")
                sys.exit()

a, b, c, d = [int(x) for x in input().split()]
while True:
    c -= b
    if c <= 0:
        print("Yes")
        exit()
    a -= d
    if a <= 0:
        print("No")
        exit()

-import sys - -input = sys.stdin.readline -    for i in range(2): -        if i == 0: -            c -= b -            if c <= 0: -                print("Yes") -                sys.exit() -        else: -            a -= d -            if a <= 0: -                print("No") -                sys.exit() +    c -= b +    if c <= 0: +        print("Yes") +        exit() +    a -= d +    if a <= 0: +        print("No") +        exit()