import math
n, m = map(int, input().split())
A = map(int, input().split())
B = map(int, input().split())
l = math.gcd(n, m)
v = pow(n//l, -1, m//l)
d = dict()
for i, b in enumerate(B):
    if b in d:
        d[b] += [i]
    else:
        d[b] = [i]
r = n*m//l
for i, a in enumerate(A):
    if a in d:
        k = i%l
        for j in d[a]:
            if j%l == k:
                c = (j-i)*v%m//l*n + i
                r = min(r, c)
print(-1 if r == n*m//l else 1+r)