def extgcd(a, b):
    """
    拡張Euclidの互除法
    INPUT:
        a, b
    OUTPUT:
        d: gcd(a, b)
        (x, y): ax + by = d の解
    """
    if b == 0:
        return a, (1, 0)
    d, (y, x) = extgcd(b, a % b)
    y -= a // b * x
    return d, (x, y)


N, M = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
g, (x, y) = extgcd(N, -M)

lcm = N * (M // -g)

ans = 10**18
for i, a in enumerate(A, 1):
    for j, b in enumerate(B, 1):
        if a != b:
            continue
        if (j - i) % g != 0:
            continue
        d = (j - i) // g
        tmp = d * N * x + i
        tmp %= lcm
        ans = min(ans, tmp)


if ans >= 10**18:
    ans = -1
print(ans)