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

for i in range(100):

    c -= b

    if c <= 0:

        print('Yes')

        break

    a -= d

    if a <= 0:

        print('No')

        break
import math

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

print(('Yes' if math.ceil(c/b) <= math.ceil(a/d) else 'No'))
a, b, c, d = list(map(int, input().split()))
for i in range(100):
    c -= b
    if c <= 0:
        print("Yes")
        break
    a -= d
    if a <= 0:
        print("No")
        break

import math

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

+import math + -for i in range(100): -    c -= b -    if c <= 0: -        print("Yes") -        break -    a -= d -    if a <= 0: -        print("No") -        break +print(("Yes" if math.ceil(c / b) <= math.ceil(a / d) else "No"))