# 分母を正にしてから分母を消去する解法

import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

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

if b < 0:
    a, b = -a, -b
if d < 0:
    c, d = -c, -d

LHS = a * d
RHS = b * c

print('Yes' if LHS < RHS else 'No')