import sys

input = sys.stdin.readline



def main():

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



    flg = False



    while a > 0 and b > 0:

        c -= b



        if c > 0:

            a -= d

        else:

            flg = True

            break



    if flg == False:

        print('No')

    else:

        print('Yes')







if __name__ == '__main__':

    main()



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



x = (a+d-1)//d

y = (c+b-1)//b



print(('Yes' if x >= y else 'No'))

import sys

input = sys.stdin.readline


def main():
    a, b, c, d = list(map(int, input().split()))
    flg = False
    while a > 0 and b > 0:
        c -= b
        if c > 0:
            a -= d
        else:
            flg = True
            break
    if flg == False:
        print("No")
    else:
        print("Yes")


if __name__ == "__main__":
    main()

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

-import sys - -input = sys.stdin.readline - - -def main(): -    a, b, c, d = list(map(int, input().split())) -    flg = False -    while a > 0 and b > 0: -        c -= b -        if c > 0: -            a -= d -        else: -            flg = True -            break -    if flg == False: -        print("No") -    else: -        print("Yes") - - -if __name__ == "__main__": -    main() +a, b, c, d = list(map(int, input().split())) +x = (a + d - 1) // d +y = (c + b - 1) // b +print(("Yes" if x >= y else "No"))