from math import gcd

X1, Y1 = map(int, input().split())
X2, Y2 = map(int, input().split())
X3, Y3 = map(int, input().split())


def solve(n, div_num, mod_num, add_num):
    for _ in range(div_num + 1):
        if n % div_num == mod_num and n:
            return n
        n += add_num
    else:
        print(-1)
        exit()


n = solve(X1, Y2, X2, Y1)
ans = solve(n, Y3, X3, Y1 * Y2 // gcd(Y1, Y2))
print(ans)