#define F_C
#include <bits/stdc++.h>
#define rep(i, l, r) for(int i = l; i < r; i++)
#define hrp(i, l, r) for(int i = l; i <= r; i++)
#define rev(i, r, l) for(int i = r; i >= l; i--)
#define int ll
using namespace std;
typedef long long ll;
template<typename tn = int> tn next(void) { tn k; cin>>k; return k; }
#ifndef LOCAL
#define D(...) 0
#endif
const int U = 1.5e3;
int w[U][U], c[U][U], l[U][U], r[U][U], u[U][U], t[U*U];
signed main(void)
{
    #ifdef LOCAL
//	freopen("C:\\Users\\Loxil\\Desktop\\IN.txt", "r", stdin);
//	freopen("C:\\Users\\Loxil\\Desktop\\OUT.txt", "w", stdout);
    #endif
    
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int n, m;
    cin>>n>>m;
    rep(i, 0, n) rep(j, 0, m) t[next()] = i*m+j+1;
    rep(i, 0, n) rep(j, 0, m) cin>>w[i][j], l[i][j] = r[i][j] = j, u[i][j] = 1;

    rep(i, 0, n) rep(j, 0, m) w[i][j] = t[w[i][j]];    

    int col = 0;
    rep(i, 0, n) rep(j, 0, m)
    {
        if (i && w[i][j] == w[i-1][j]+m) c[i][j] = c[i-1][j];
        else if (j && w[i][j] == w[i][j-1]+1) c[i][j] = c[i][j-1];
        else c[i][j] = ++col;
    }

    rep(i, 0, n) rep(j, 1, m) if (c[i][j] == c[i][j-1]) l[i][j] = l[i][j-1];
    rep(i, 0, n) rev(j, m-2, 0) if (c[i][j] == c[i][j+1]) r[i][j] = r[i][j+1];

    int ans = 0;
    rep(i, 0, n) rep(j, 0, m)
    {
        if (i && c[i][j] == c[i-1][j])
        {
            l[i][j] = max(l[i][j], l[i-1][j]);
            r[i][j] = min(r[i][j], r[i-1][j]);
            u[i][j] = u[i-1][j]+1;
        }
        ans = max(ans, (r[i][j]-l[i][j]+1)*u[i][j]);
    }

    cout<<ans<<endl;

    // rep(i, 0, n) rep(j, 0, m) cout<<w[i][j]<<" \n"[j == m-1];
    rep(i, 0, n) rep(j, 0, m) cout<<c[i][j]<<" \n"[j == m-1];

    return 0;
}
/*

 */