#!/usr/bin/python3

# -*- coding: utf-8 -*-

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

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

    print("Yes")

else:

    print("No")

    
#!/usr/bin/python3

# -*- coding: utf-8 -*-

import math

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

if math.ceil(c / b) <= math.ceil(a / d):

    print("Yes")

else:

    print("No")

    
#!/usr/bin/python3
# -*- coding: utf-8 -*-
a, b, c, d = list(map(int, input().split()))
if (c + b - 1) // b <= (a + d - 1) // d:
    print("Yes")
else:
    print("No")

#!/usr/bin/python3
# -*- coding: utf-8 -*-
import math

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

+import math + -if (c + b - 1) // b <= (a + d - 1) // d: +if math.ceil(c / b) <= math.ceil(a / d):