#!/usr/bin/env python2
# coding: utf-8

def extgcd(a, b):
    x,y, u,v = 0,1, 1,0
    while a != 0:
        q, r = b/a, b%a
        m, n = x-u*q, y-v*q
        b,a, x,y, u,v = a,r, u,v, m,n
        g = b
    return x, y, g


def solve():
    a, b = 0, 1
    for i in xrange(3):
        na, nb = map(int, raw_input().split())
        x, y, g = extgcd(b, nb)
        if a%g != na%g:
            print -1; return
        l = b/g*nb
        a, b = ((a+(na-a)/g*x*b)%l, l)

    if a == 0:
        a = b

    print a

solve()