def crt(rs,ms):
    def extgcd(a,b):
        if b==0:
            return 1,0,a
        else:
            c,x,g=extgcd(b,a%b)
            return x,c-a//b*x,g
    
    r1,m1=0,1
    
    for r2,m2 in zip(rs,ms):
        p,q,g=extgcd(m1,m2)

        if r1%g!=r2%g:
            return 0,0

        s=(r2-r1)//g

        l=m1//g*m2
        x=(s*m1*p+r1)%l

        m1=l
        r1=x
    
    return r1,m1

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

r,m=crt(X,Y)

if r==0 and m==0:
    print(-1)
elif r==0:
    print(m)
else:
    print(r)