#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define mp make_pair
using namespace std;
void db() {cout << endl;}
template <typename T, typename ...U> void db(T a, U ...b) {
//return;
cout << a << ' ', db(b...);
}
#ifdef Cloud
#define file freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#else
#define file ios::sync_with_stdio(false); cin.tie(0)
#endif
const int N = 3001;
signed main(){
file;
int n, m;
cin >> n >> m;
int a[n][m];
for (int i = 0; i < n; i++)
for (int j = 0; j < m; j++)
cin >> a[i][j];
int mi[n][m], ans = -1;
for (int i = 0; i < n; i++){
for (int j = 0; j < m; j++){
if (!i and !j) mi[i][j] = a[i][j] - i - j;
else if (!i) mi[i][j] = min(mi[i][j - 1], a[i][j] - i - j);
else if (!j) mi[i][j] = min(mi[i - 1][j], a[i][j] - i - j);
else mi[i][j] = min({mi[i - 1][j], mi[i][j - 1], a[i][j] - i - j});
ans = max(ans, a[i][j] - i - j - mi[i][j] - 1);
}
}
//db(ans);
for (int i = 0; i < n; i++){
for (int j = m - 1; j >= 0; j--){
if (!i and j == m - 1) mi[i][j] = a[i][j] - i + j;
else if (!i) mi[i][j] = min(mi[i][j + 1], a[i][j] - i + j);
else if (j == m - 1) mi[i][j] = min(mi[i - 1][j], a[i][j] - i + j);
else mi[i][j] = min({mi[i - 1][j], mi[i][j + 1], a[i][j] - i + j});
ans = max(ans, a[i][j] - i + j - mi[i][j] - 1);
}
}
for (int i = n - 1; i >= 0; i--){
for (int j = 0; j < m; j++){
if (i == n - 1 and !j) mi[i][j] = a[i][j] + i - j;
else if (i == n - 1) mi[i][j] = min(mi[i][j - 1], a[i][j] + i - j);
else if (!j) mi[i][j] = min(mi[i + 1][j], a[i][j] + i - j);
else mi[i][j] = min({mi[i + 1][j], mi[i][j - 1], a[i][j] + i - j});
ans = max(ans, a[i][j] + i - j - mi[i][j] - 1);
}
}
for (int i = n - 1; i >= 0; i--){
for (int j = m - 1; j >= 0; j--){
if (i == n - 1 and j == m - 1) mi[i][j] = a[i][j] + i + j;
else if (i == n - 1) mi[i][j] = min(mi[i][j + 1], a[i][j] + i + j);
else if (j == m - 1) mi[i][j] = min(mi[i + 1][j], a[i][j] + i + j);
else mi[i][j] = min({mi[i + 1][j], mi[i][j + 1], a[i][j] + i + j});
ans = max(ans, a[i][j] + i + j - mi[i][j] - 1);
}
}
cout << ans;
}
