#!/usr/bin/python from fractions import gcd def extgcd(x, y): if y == 0: return 1, 0, x a, b, d = extgcd(y, x%y) return b, a-x/y*b, d def mod_inv(a, div): x, y, d = extgcd(a, div) return x % div if d==1 else None def linear_congruence(A, B, M): x, m = 0, 1 for i in xrange(len(A)): a, b = A[i] * m, B[i] - A[i] * x d = gcd(M[i], a) if(b % d != 0): return 0, -1 t = b / d * mod_inv(a/d, M[i]/d) % (M[i] / d) x = x + m * t m *= M[i] / d return x % m, m N = 3 xys = [map(int, raw_input().split()) for _ in xrange(N)] zipped = zip(*xys) res = linear_congruence([1] * N, *(zipped)) if res[1] == -1: print -1 else: print res[0] or res[1]