#include <bits/stdc++.h>
using namespace std;
int n, m;
#define C 1005
#define D 1000005
int a[C][C], b[C][C], idx[D], idy[D], v[C][C];
int r[C], l[C];
vector<pair<int, int>> g[C];
 
long long monotonestack(int row, int st, int ed){
	for(int i = st; i <= ed; ++i) r[i] = ed + 1, l[i] = st - 1;
	stack<int> s;
	for(int i = st; i <= ed; ++i){
		while(!s.empty() && v[row][i] < v[row][s.top()]){
			r[s.top()] = i;
			s.pop();
		}
		s.push(i);
	}
	while(!s.empty()) s.pop();
	for(int i = ed; i >= st; --i){
		while(!s.empty() && v[row][i] < v[row][s.top()]){
			l[s.top()] = i;
			s.pop();
		}
		s.push(i);
	}
	long long ans = 0ll;
	for(int i = st; i <= ed; ++i){
		ans = max(ans, 1ll * (r[i] - l[i] - 1) * v[row][i]);
	}
	return ans;
}
 
signed main(int argc, char** argv){
    cin.tie(0) -> sync_with_stdio(0);
    cin >> n >> m;
	for(int i = 1; i <= n; ++i) for(int j = 1; j <= m; ++j) cin >> a[i][j], idx[a[i][j]] = i, idy[a[i][j]] = j;
	for(int i = 1; i <= n; ++i) for(int j = 1; j <= m; ++j) cin >> b[i][j];
	for(int i = 1; i <= n; ++i){
		int st = 1, ed = 1;
		for(int j = 1; j <= m; ++j){
			if(!idx[b[i][j]] || !idy[b[i][j]]) v[i][j] = 0;
			else{
				v[i][j] = 1;
				if(i-1 >= 1 && idx[b[i][j]] == idx[b[i-1][j]]+1 && idy[b[i][j]] == idy[b[i-1][j]]){
					v[i][j] = v[i-1][j]+1;
				}
			}
			if(j-1 >= 1 && idy[b[i][j]] == idy[b[i][j-1]]+1 && idx[b[i][j]] == idx[b[i][j-1]]){
				ed = j;
			}else if(j != 1){
				g[i].push_back(make_pair(st, ed));
				st = j;
				ed = j;
			}
		}
		g[i].push_back(make_pair(st, m));
	}
	long long ans = 0ll;
	for(int i = 1; i <= n; ++i){
		for(const auto& [st, ed]: g[i]){
			ans = max(monotonestack(i, st, ed), ans);
		}
	}
	cout << ans << "\n";
}