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

for _ in range(a//d):

    c=c-b

    if c<=0:

        print("Yes")

        exit()

    a=a-d

    if a<=0:

        print("No")

        exit()

if c-b<=0:print("Yes")

else:print("No")

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

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

    print("Yes")

else:print("No")
a, b, c, d = list(map(int, input().split()))
for _ in range(a // d):
    c = c - b
    if c <= 0:
        print("Yes")
        exit()
    a = a - d
    if a <= 0:
        print("No")
        exit()
if c - b <= 0:
    print("Yes")
else:
    print("No")

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

-for _ in range(a // d): -    c = c - b -    if c <= 0: -        print("Yes") -        exit() -    a = a - d -    if a <= 0: -        print("No") -        exit() -if c - b <= 0: +if (a + d - 1) // d >= (c + b - 1) // b: