from sys import stdin, stdout

import math

import bisect

import queue



a, b, c, d = list(map(int, stdin.readline().strip().split()))



while True:

    c -= b

    if c <= 0:

        stdout.writelines('Yes\n')

        break

    a -= d

    if a <= 0:

        stdout.writelines('No\n')

        break

import math

a,b,c,d=list(map(int,input().split(' ')))

jojo=math.ceil(a/d)

dio=math.ceil(c/b)

if jojo>=dio:

    print('Yes')

else:

    print('No')
from sys import stdin, stdout
import math
import bisect
import queue

a, b, c, d = list(map(int, stdin.readline().strip().split()))
while True:
    c -= b
    if c <= 0:
        stdout.writelines("Yes\n")
        break
    a -= d
    if a <= 0:
        stdout.writelines("No\n")
        break

import math

a, b, c, d = list(map(int, input().split(" ")))
jojo = math.ceil(a / d)
dio = math.ceil(c / b)
if jojo >= dio:
    print("Yes")
else:
    print("No")

-from sys import stdin, stdout -import bisect -import queue -a, b, c, d = list(map(int, stdin.readline().strip().split())) -while True: -    c -= b -    if c <= 0: -        stdout.writelines("Yes\n") -        break -    a -= d -    if a <= 0: -        stdout.writelines("No\n") -        break +a, b, c, d = list(map(int, input().split(" "))) +jojo = math.ceil(a / d) +dio = math.ceil(c / b) +if jojo >= dio: +    print("Yes") +else: +    print("No")