XY = [list(map(int,input().split())) for _ in range(3)]
X,Y = map(list,zip(*XY))

def extended_euclid(a, b):
    if b == 0:
        return (1, 0)
    else:
        xd, yd = extended_euclid(b, a % b)
        return (yd, xd - a // b * yd)

from math import gcd,lcm

x, y = 0, 1
for i in range(3):
    x0, y0 = XY[i]
    d = gcd(y,y0)
    y //= d
    y0 //= d
    p, q = extended_euclid(y, y0)
    x = (x0 * y * p + x * y0 * q) % (y * y0 * d)
    y *= y0 * d
r = x
m = y
for x,y in XY:
    if r % y != x:
        print(-1)
        exit()
if r == 0:
    print(lcm(*Y))
else:
    print(r)