def read_data():
    x1, y1 = map(int, input().split())
    x2, y2 = map(int, input().split())
    x3, y3 = map(int, input().split())
    return x1, y1, x2, y2, x3, y3


def gcd_ext(m: int, n: int) -> (int, int, int):
    '''拡張ユークリッドの互除法
    mx + ny = gcd(x, y)
    となる、gcd(x, y), x, y を返す。
    '''
    x, y, u, v = 1, 0, 0, 1
    while n:
        k, m = divmod(m, n)
        m, n = n, m
        x, y, u, v = u, v, x - u * k, y - v * k
    return m, x, y


def solve2(x1, y1, x2, y2):
    gcd, a, b = gcd_ext(y1, y2)
    lcm = y1 * y2 // gcd
    k, r = divmod(x1 - x2, gcd)
    if r != 0:
        return -1, lcm
    z = (x1 - k * a * y1) % lcm
    #  z = (x2 + k * b * y2) % lcm
    return z, lcm


def solve3(x1, y1, x2, y2, x3, y3):
    x12, y12 = solve2(x1, y1, x2, y2)
    if x12 == -1: return -1
    #  z % y12 = x12 and z % y3 = x3
    z, lcm = solve2(x12, y12, x3, y3)
    return z


x1, y1, x2, y2, x3, y3 = read_data()
print(solve3(x1, y1, x2, y2, x3, y3))