# 入力のvalidation用。
# RE にならず WA になればOK。
import sys

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

nums = list(map(int, read().split()))

A = 4 * 10**9
assert len(nums) == 4
a, b, c, d = nums

assert -A <= a <= A
assert -A <= b <= A
assert -A <= c <= A
assert -A <= d <= A

assert d != 0
assert c != 0