from sys import stdin
from fractions import gcd
readline = stdin.readline


def lcm(a, b):
    return a * b // gcd(a, b)


def extended_gcd(x, y):
    if y == 0:
        return 1, 0, x
    a, b, c = extended_gcd(y, x % y)
    return b, a - x // y * b, c


xy = [map(int, readline().split()) for _ in range(3)]

xx, yy = 0, 1

for x, y in xy:
    a, b, c = extended_gcd(yy, y)
    d, m = divmod(abs(xx - x), c)
    if m:
        print(-1)
        break
    l = lcm(yy, y)
    xx = (yy * abs(a) * d + xx) % l
    yy = l
else:
    print(xx)