from math import gcd
a,b = map(int,input().split())
if a==0: a = b
for _ in range(2):
    x,y = map(int,input().split())
    for i in range(y):
        if a%y == x: break
        a += b
    else:
        print(-1)
        exit()
    b *= y//gcd(b,y)
print(a)