import math



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



ans1 = math.ceil(a / d)

ans2 = math.ceil(c / b)



if ans1 < ans2:

  print('No')

else:

  print('Yes')

import math



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



num1 = math.ceil(c / b)

num2 = math.ceil(a / d)



if num1 <= num2:

    print('Yes')

else:

    print('No')

import math

a, b, c, d = list(map(int, input().split()))
ans1 = math.ceil(a / d)
ans2 = math.ceil(c / b)
if ans1 < ans2:
    print("No")
else:
    print("Yes")

import math

a, b, c, d = list(map(int, input().split()))
num1 = math.ceil(c / b)
num2 = math.ceil(a / d)
if num1 <= num2:
    print("Yes")
else:
    print("No")

-ans1 = math.ceil(a / d) -ans2 = math.ceil(c / b) -if ans1 < ans2: +num1 = math.ceil(c / b) +num2 = math.ceil(a / d) +if num1 <= num2: +    print("Yes") +else: -else: -    print("Yes")