def extgcd(a,b):
    if b==0:
        return a,1,0
    else:
        r,p=a//b,a%b
        g,x,y=extgcd(b,p)
        return g,y,x-r*y

def crt(B,M):
    r,z=0,1
    for b,m in zip(B,M):
        b1,m1=r,z
        b2,m2=b,m
        g,x,y=extgcd(m1,m2)
        x,y=(b2-b1)//g*x,(b2-b1)//g*y
        if b1%g!=b2%g:
            return (0,0)
        a=(m1*x+b1)%(m1*m2//g)
        r,z=a,m1*m2//g
    return r,z

b,m=[],[]
for _ in range(3):
    x,y=map(int,input().split())
    b.append(x)
    m.append(y)

r,z=crt(b,m)
if r==0 and z==0:
    print(-1)
else:
    print(r)