# coding=utf-8
x = [0] * 3
y = [0] * 3
ans = [[] for i in range(3)]
def xy(y, x):
    r = []
    i = 0
    while x * i + y < 10 ** 6:
        r.append(x * i + y)
        i += 1
    return r

for i in range(3):
    x[i], y[i] = map(int, input().split())
for i in range(3):
    ans[i] = xy(x[i], y[i])

ans2 = set(ans[0]) & set(ans[1]) & set(ans[2])
if len(ans2) == 0:
    print('-1')
else:
    print(min(ans2))