#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define RFOR(i, a, b) for (int i = (a) - 1; i >= (b); i--)
#define FILL(a, b) memset(a, b, sizeof(a))
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

struct DSU
{
	int n;
	VI p, sz;
	void init(int _n)
	{
		n = _n;
		p.resize(n);
		iota(ALL(p), 0);
		sz.assign(n, 1);
	}
	int find(int v)
	{
		if (p[v] == v) 
		{
			return v;
		}
		return p[v] = find(p[v]);
	}
	void unite(int u, int v)
	{
		u = find(u);
		v = find(v);
		if (u == v)
			return;
		if (sz[u] > sz[v])
			swap(u, v);
		p[u] = v;
		sz[v] += sz[u];
	}
};

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int n, m;
	cin >> n >> m;
	vector a(n, vector<int>(m)), b(n, vector<int>(m)), h(n, vector<int>(m));
	vector<int> pos(n * m);
	FOR(i, 0, n)
	{
		FOR(j, 0, m)
		{
			cin >> a[i][j];
			a[i][j]--;
			pos[a[i][j]] = m * i + j;
		}
	}
	FOR(i, 0, n)
	{
		FOR(j, 0, m)
		{
			cin >> b[i][j];
			b[i][j]--;
			b[i][j] = pos[b[i][j]];
		}
	}
	DSU dsu;
	vector<int> vec;
	vector<int> used(m);
	int ans = 0;
	FOR(i, 0, n)
	{
		FOR(j, 0, m)
			h[i][j] = i > 0 && b[i - 1][j] == b[i][j] - m ? h[i - 1][j] + 1 : 1;
		dsu.init(m);
		used.assign(m, 0);
		for (int l = 0; l < m; l++)
		{
			int r = l;
			vec.clear();
			while (r < m && (r == l || b[i][r + 1] == b[i][r] + 1))
				vec.push_back(r++);
			vec.push_back(r);
			sort(ALL(vec), [&](int j1, int j2){return h[i][j1] > h[i][j2];});
			for (int j : vec)
			{
				used[j] = 1;
				if (j - 1 >= l && used[j - 1])
					dsu.unite(j, j - 1);
				if (j + 1 <= r && used[j + 1])
					dsu.unite(j, j + 1);
				ans = max(ans, dsu.sz[dsu.find(j)] * h[i][j]);
			}
			l = r;
		}
	}
	cout << ans << "\n";
}