import itertools

import math

import fractions

import functools

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





# if c // b > a // d:

#     print("Yes")

# else:

#     print("No")



while c > 0 and a > 0:

    c = c - b

    if c <= 0:

        print('Yes')

        quit()

    a = a - d

    if a<= 0:

        print("No")

        quit()

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





if (c+b-1) // b <= (a+d-1) // d:

    print("Yes")

else:

    print("No")
import itertools
import math
import fractions
import functools

a, b, c, d = list(map(int, input().split()))
# if c // b > a // d:
#     print("Yes")
# else:
#     print("No")
while c > 0 and a > 0:
    c = c - b
    if c <= 0:
        print("Yes")
        quit()
    a = a - d
    if a <= 0:
        print("No")
        quit()

a, b, c, d = list(map(int, input().split()))
if (c + b - 1) // b <= (a + d - 1) // d:
    print("Yes")
else:
    print("No")

-import itertools -import math -import fractions -import functools - -# if c // b > a // d: -#     print("Yes") -# else: -#     print("No") -while c > 0 and a > 0: -    c = c - b -    if c <= 0: -        print("Yes") -        quit() -    a = a - d -    if a <= 0: -        print("No") -        quit() +if (c + b - 1) // b <= (a + d - 1) // d: +    print("Yes") +else: +    print("No")