import math

N, M = map(int, input().split())
A = map(int, input().split())
B = map(int, input().split())

D = dict()
g = math.gcd(N, M)
p = pow(N//g, -1, M//g)

for i, b in enumerate(B):
    if b in D:
        D[b] += [i]
    else:
        D[b] = [i]

l = N*M//g

for i, a in enumerate(A):
    if a in D:
        k = i%g
        for j in D[a]:
            if j%g == k:
                l = min(l, (j-i)*p%M//g*N + i)

print(-1 if l == N*M//g else 1+l)