x1, y1 = map(int, input().split())
x2, y2 = map(int, input().split())
x3, y3 = map(int, input().split())
for i in range(1, 100000001):
    j = 0
    j += 1 if i % y1 == x1 else 0
    j += 1 if i % y2 == x2 else 0
    j += 1 if i % y3 == x3 else 0
    if j == 3:
        print(i)
        break
else:
    print(-1)