def gcd_ext(a, b):   
    '''
    1次不定方程式 ax+by=gcd(a, b) の解と最大公約数を返す。負の値には未対応
    x, y, gcd(a, b)
    '''
    if a < b:
        x, y, s = gcd_ext(b, a)
        return y, x, s
    s, xs, ys = a, 1, 0
    t, xt, yt = b, 0, 1

    while t > 0:
        n = s // t
        s, t = t, s % t
        xs, xt = xt, xs - n * xt
        ys, yt = yt, ys - n * yt
    return xs, ys, s


def crt(b, m):
    '''
    すべてのiについて x≡b[i](mod, m[i]) の論理積を満たす x と lcm(m[:]) を求める。
    解がない場合 -1, 0 を返す
    '''
    n = len(b)
    assert n == len(m)
    m0, b0 = 1, 0
    for i in range(n):
        m1, b1 = m[i], b[i] % m[i]
        p, _, d = gcd_ext(m0, m1) # m0 * p + m1 * q = gcd(m0, m1)
        if (b1 - b0) % d: # b0 ≡ b1 (mod gcd(m0, m1)) の不成立
            return -1, 0
        lcm = m0 * m1 // d
        b0 = (b0 + (b1 - b0) // d * p * m0) % lcm
        m0 = lcm
    return b0, lcm

import sys
xy = list(map(int, sys.stdin.read().split()))
x = xy[0::2]
y = xy[1::2]
ans, _ = crt(x, y)
print(ans)