import sys
input = lambda : sys.stdin.readline().rstrip()
sys.setrecursionlimit(max(1000, 10**9))
write = lambda x: sys.stdout.write(x+"\n")


xy = [tuple(map(int, input().split())) for _ in range(3)]
from math import gcd
def gcd2(a, b):
    """a*x + b*y = gcd(a,b)なるx,yも求める
    """
    l = []
    while b:
        l.append(divmod(a,b))
        a, b = b, a%b
    x, y = 1, 0
    for aa,bb in l[::-1]:
        x, y = y, x - aa*y
    return a, x, y
def modinv(x, M):
    """素数ではないM、Mと互いに素なxに対し
    x * y == 1 mod M なるyを求める
    """
    a,xx,yy = gcd2(x,M)
#     l = []
#     while M:
#         l.append(divmod(x,M))
#         x, M = M, x%M
#     xx, yy = 1, 0
#     for aa,bb in l[::-1]:
#         xx, yy = yy, xx - aa*yy
    return a,xx%M
def crt(rs, ms):
    """x == rs[i] mod ms[i] をみたすxをを求め、(x, l(=ms))を返す
    (そのようなxは x + i * lとして書ける)
    存在しない場合はNoneを返す
    長さが0の配列を渡すと(0,1)を返す
    """
    r0 = 0
    m0 = 1
    for r1,m1 in zip(rs, ms):
        if m0<m1:
            m0, m1 = m1, m0
            r0, r1 = r1, r0
        if m0%m1==0:
            if r0%m1 != r1:
                return None,None
            else:
                continue
#         print(m0,m1)
        g,im = modinv(m0, m1)
        u1 = m1//g
        if (r1-r0)%g!=0:
            return None,None
        x = (r1-r0) // g % u1 * im % u1
        r0 += x * m0
        m0 *= u1
        if r0<0:
            r0 += m0
    return r0,m0
r,m = crt([item[0] for item in xy], [item[1] for item in xy])
if r is not None:
    if r==0:
        r += m
    print(r)
else:
    print(-1)