import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
sys.setrecursionlimit(10 ** 7)

l, r, m, k = map(int, read().split())
for i in range(1, min(k, 10 ** 6) + 1):
    if r * i >= m and r * i - m <= (r - l) * i:
        print('Yes')
        exit()
else:
    if k == 0:
        print('Yes')
    else:
        print('No')