A = [list(map(int, input().split())) for _ in range(3)]


def inv_gcd(a, b):
    a = a % b
    if a == 0:
        return (b, 0)
    s = b
    t = a
    m0 = 0
    m1 = 1
    while(t):
        u = s//t
        s -= t*u
        m0 -= m1*u
        s, t = t, s
        m0, m1 = m1, m0
    if m0 < 0:
        m0 += b//s
    return (s, m0)


def inv_mod(x, m):
    assert 1 <= m
    z = inv_gcd(x, m)
    assert z[0] == 1
    return z[1]


def crt(r, m):
    assert len(r) == len(m)
    n = len(r)
    r0 = 0
    m0 = 1
    for i in range(n):
        assert 1 <= m[i]
        r1 = r[i] % m[i]
        m1 = m[i]
        if m0 < m1:
            r0, r1 = r1, r0
            m0, m1 = m1, m0
        if (m0 % m1 == 0):
            if (r0 % m1 != r1):
                return (0, 0)
            continue
        g, im = inv_gcd(m0, m1)
        u1 = m1//g
        if ((r1-r0) % g):
            return (0, 0)
        x = (r1-r0)//g % u1*im % u1
        r0 += x*m0
        m0 *= u1
        if r0 < 0:
            r0 += m0
    return (r0, m0)


r = [A[i][0] for i in range(3)]
m = [A[i][1] for i in range(3)]
ans = crt(r, m)
if ans[1] == 0:
    print(-1)
else:
    print(ans[0]+ans[1]*(ans[0] == 0))