#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("-O3")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define mp make_pair
#define ll long long
#define ld long double
#define pb push_back
#define fast_io ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define fs first
#define sc second
#define getfiles ifstream cin("input.txt"); ofstream cout("output.txt");
#define endl '\n'
#define pii pair<int, int>
const int INF = 2000000005;
const ll BIG_INF = 2000000000000000005;
const int mod = 1000000007;
const int P = 31;
const ld PI = 3.141592653589793238462643;
const double eps = 1e-9;
using namespace std;
using namespace __gnu_pbds;
bool valid(int x, int y, int n, int m) {
return x >= 0 && y >= 0 && x < n && y < m;
}
mt19937 rng(1999999973);
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
const int N = 1005;
int a[N][N], n, m, curVal[N], suf[N], pref[N], ans = 0;
inline void update(int x) {
for (int i = 0; i < m; i++) {
curVal[i] = min(curVal[i], a[x][i] - x);
}
int curMin = INF;
for (int i = 0; i < m; i++) {
curMin = min(curMin, curVal[i] - i);
pref[i] = curMin;
}
curMin = INF;
for (int i = m - 1; i >= 0; i--) {
curMin = min(curMin, curVal[i] + i);
suf[i] = curMin;
}
}
inline void repeat() {
for (int i = 0; i < N; i++) {
curVal[i] = INF;
}
for (int x = 0; x < n; x++) {
update(x);
for (int y = 0; y < m; y++) {
ans = max(ans, a[x][y] - pref[y] - y - x);
ans = max(ans, a[x][y] - suf[y] + y - x);
}
}
}
signed main() {
fast_io;
//getfiles;
cin >> n >> m;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cin >> a[i][j];
}
}
repeat();
for (int i = 0; i < n; i++) {
reverse(a[i], a[i] + m);
}
for (int i = 0; i < n - 1 - i; i++) {
for (int j = 0; j < m; j++) {
swap(a[i][j], a[n - 1 - i][j]);
}
}
repeat();
cout << ans - 1;
return 0;
}
