#include <bits/stdc++.h>
#define qqbb ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define all(x) (x).begin(), (x).end()
#define int long long
#define endl '\n'
#define _ <<' '<<
#define lb(x) x & -x
#define AA cerr<<"AA"<<endl;
using namespace std;
typedef pair<int, int> pii;
const int inf = 0x3f3f3f3f;

const int N = 2e5 + 10, M = 4e5 + 10;

int vis[1010][1010];
int ma[1010][1010];
int mb[1010][1010];
int n,m;
map<int,pii> mpa;
map<int,pii> mpb;
int dir[4][2] = {0, 1, 0, -1, 1, 0, -1, 0};

int cnt = 0;
int le[1010],ri[1010];
int lo[1010],hi[1010];
int h[1010][1010],l[1010][1010],r[1010][1010];

bool check(int x, int y,int detx,int dety){
    if(vis[x][y] || x<1 || x>n || y<1 || y>m) return false;
    if(detx<1 || detx>n || dety<1 || dety>m) return false;
    if(ma[x][y] != mb[detx][dety]) return false;
    return true;
}
void bfs(int sx,int sy){
    queue<pii> q;
    q.push({sx,sy});
    while (!q.empty()){
        int x = q.front().first;
        int y = q.front().second;
        le[cnt] = min(le[cnt],y);
        ri[cnt] = max(ri[cnt],y);
        lo[cnt] = min(lo[cnt],x);
        hi[cnt] = max(hi[cnt],x);
        q.pop();
        vis[x][y] = cnt;
        for (int i = 0; i < 4; i++){
            int nx = x + dir[i][0];
            int ny = y + dir[i][1];
            int detx = mpb[ma[x][y]].first + dir[i][0];
            int dety = mpb[ma[x][y]].second + dir[i][1];
            if (check(nx,ny,detx,dety)){
                q.push({nx,ny});   
            }
        }
    }
}


void solve(){
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            cin>>ma[i][j];
            mpa[ma[i][j]] = {i,j};
        }
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            cin>>mb[i][j];
            mpb[mb[i][j]] = {i,j};
        }
    }
    for(int i=1;i<=1009;i++){
        le[i] = inf;
        lo[i] = inf;
        ri[i] = -1;
        hi[i] = -1;
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            if(vis[i][j] == 0){
                cnt++;
                bfs(i,j);
            }
        }
    }
    // for(int i=1;i<=cnt;i++){
    //     int ans = 0;
    //     for(int res=1;res<=ri[i]-le[i]+1;res++){
    //         for(int loo = lo[i];loo<=hi[i];loo++){
    //             for(int x = le[i];x<=le[i] + res -1;x++){
    //                 if(vis[loo][x]){

    //                 }
    //             }
    //         }   
    //     }
    // }
    int res = -inf;
    for (int tgt = 1;tgt<=cnt;tgt++){
        // cout<<lo[tgt] _ hi[tgt] _ le[tgt] _ ri[tgt]<<endl;

        int ans = 0;
        for(int i=lo[tgt];i<=hi[tgt];i++){
            for(int j=le[tgt];j<=ri[tgt];j++){
                h[i][j] = 1;
                r[i][j] = l[i][j] = j;
            }
            for(int j=le[tgt]+1;j<=ri[tgt];j++)
                if (vis[i][j] == tgt && vis[i][j-1] == tgt)
                    l[i][j] = l[i][j-1];
            for(int j=ri[tgt]-1;j>le[tgt];j--){
                if (vis[i][j] == tgt && vis[i][j+1] == tgt)
                    r[i][j] = r[i][j+1];
            }
        }
        for(int i=lo[tgt];i<=hi[tgt];i++){
            for(int j=le[tgt];j<=ri[tgt];j++){
                if (i>lo[tgt] && vis[i][j] == tgt){
                    if (vis[i-1][j] == tgt){
                        h[i][j] = h[i-1][j]+1;
                        if (l[i-1][j] > l[i][j])
                            l[i][j] = l[i-1][j];
                        if (r[i-1][j] < r[i][j])
                            r[i][j] = r[i-1][j];
                    }
                    if ((r[i][j]-l[i][j]+1)*h[i][j]>ans)
                        ans = (r[i][j]-l[i][j]+1) * h[i][j];
                }
            }
        }
        res = max(res,ans);
    }
    // cout<<endl;
    // for(int i=1;i<=n;i++){
    //     for(int j=1;j<=m;j++){
    //         cout<<vis[i][j]<<' ';
    //     }
    //     cout<<endl;
    // }
    cout<<res;
}

signed main(){
    qqbb;
//	cout<<fixed<<setprecision(0);
    int Test=1;
//	cin>>Test;
    while(Test--){
        solve();
    }
    return 0;
}