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

while True:

    c-=b

    if c<=0:

        print("Yes")

        exit()

    a-=d

    if a<=0:

        print("No")

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

taka=int((c+b-1)/b)

aoki=int((a+d-1)/d)



if taka<=aoki:

    print("Yes")

else:

    print("No")
a, b, c, d = list(map(int, input().split()))
while True:
    c -= b
    if c <= 0:
        print("Yes")
        exit()
    a -= d
    if a <= 0:
        print("No")
        exit()

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

-while True: -    c -= b -    if c <= 0: -        print("Yes") -        exit() -    a -= d -    if a <= 0: -        print("No") -        exit() +taka = int((c + b - 1) / b) +aoki = int((a + d - 1) / d) +if taka <= aoki: +    print("Yes") +else: +    print("No")