def extgcd(a, b):
    """returns gcd(a, b), s, r s.t. a * s + b * r == gcd(a, b)"""
    s, bs = 0, 1
    r, br = b, a
    while r:
        q = br // r
        br, r = r, br - q * r
        bs, s = s, bs - q * s
    return br, bs, (br-bs*a)//b if b else 0

def crt(V):
    """最小のxと最小公倍数dを返す"""
    x = 0; d = 1
    for X, Y in V:
        g, a, b = extgcd(d, Y)
        x, d = (Y*b*x + d*a*X) // g, d*(Y // g)
        x %= d
    return x, d

a = [list(map(int, input().split())) for _ in range(3)]
x,d = crt(a)
for X,Y in a:
    if x%Y!=X:
        print(-1)
        exit()
print(x if x else x+d)