#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
using namespace std;
#define int long long int
const int N = 1e3 + 100;
const int md = 1e9 + 7;
const int INF = 1e10 + 1;
int n, m;
vector<vector<int>> a(N, vector<int> (N));
struct segtree {
vector<vector<vector<int>>> tree;
int size_n, size_m;
void init(int n, int m) {
size_n = 1, size_m = 1;
while (size_n < n) size_n <<= 1;
while (size_m < m) size_m <<= 1;
tree.assign(2 * size_n, vector<vector<int>> (2 * size_m, vector<int> (4, INF)));
}
void build_y(int cx, int lx, int rx, int cy, int ly, int ry) {
if (ry - ly == 1) {
if (rx - lx == 1) {
if (lx < n && ly < m) {
tree[cx][cy][0] = a[lx][ly] - lx - ly;
tree[cx][cy][1] = a[lx][ly] + lx - ly;
tree[cx][cy][2] = a[lx][ly] - lx + ly;
tree[cx][cy][3] = a[lx][ly] + lx + ly;
}
}
else {
for (int i = 0; i < 4; i++)
tree[cx][cy][i] = min(tree[2 * cx + 1][cy][i], tree[2 * cx + 2][cy][i]);
}
} else {
int m = (ly + ry) >> 1;
build_y(cx, lx, rx, 2 * cy + 1, ly, m);
build_y(cx, lx, rx, 2 * cy + 2, m, ry);
for (int i = 0; i < 4; i++)
tree[cx][cy][i] = min(tree[cx][2 * cy + 1][i], tree[cx][2 * cy + 2][i]);
}
}
void build_x(int cx, int lx, int rx) {
if (rx - lx == 1) {
build_y(cx, lx, rx, 0, 0, size_m);
return;
}
int m = (lx + rx) >> 1;
build_x(2 * cx + 1, lx, m);
build_x(2 * cx + 2, m, rx);
build_y(cx, lx, rx, 0, 0, size_m);
}
void build(int n, int m) {
init(n, m);
build_x(0, 0, size_n);
}
vector<int> sum_y(int cx, int cy, int tly, int try_, int ly, int ry) {
if (tly >= ry || ly >= try_) {
return {INF, INF, INF, INF};
}
if (ly >= tly && ry <= try_) {
return tree[cx][cy];
}
int m = (ly + ry) >> 1;
vector<int> v = sum_y (cx, cy * 2 + 1, tly, try_, ly, m);
vector<int> v1 = sum_y (cx, cy * 2 + 2, tly, try_, m, ry);
return {min(v[0], v1[0]), min(v[1], v1[1]), min(v[2], v1[2]), min(v[3], v1[3])};
}
vector<int> sum_x(int cx, int tlx, int trx, int lx, int rx, int ly, int ry) {
if (tlx >= rx || lx >= trx) {
return {INF, INF, INF, INF};
}
if (lx >= tlx && rx <= trx) {
return sum_y(cx, 0, ly, ry, 0, size_m);
}
int m = (lx + rx) >> 1;
vector<int> v = sum_x (cx * 2 + 1, tlx, trx, lx, m, ly, ry);
vector<int> v1 = sum_x (cx * 2 + 2, tlx, trx, m, rx, ly, ry);
return {min(v[0], v1[0]), min(v[1], v1[1]), min(v[2], v1[2]), min(v[3], v1[3])};
}
vector<int> sum(int x1, int y1, int x2, int y2) {
return sum_x(0, x1, x2, 0, size_n, y1, y2);
}
};
int32_t main(int32_t argc, char *argv[]) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int T = 1;
// cin >> T;
while (T--) {
cin >> n >> m;
for (int i = 0; i < n; i++)
for (int j = 0; j < m; j++)
cin >> a[i][j];
segtree st;
st.build(n, m);
int ans = -1;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (true) {
vector<int> v = st.sum(0, 0, i + 1, j + 1);
ans = max(ans, (a[i][j] - i - j) - v[0] - 1);
}
if (true) {
vector<int> v = st.sum(i, 0, n, j + 1);
ans = max(ans, (a[i][j] + i - j) - v[1] - 1);
}
if (true) {
vector<int> v = st.sum(0, j, i + 1, m);
ans = max(ans, (a[i][j] - i + j) - v[2] - 1);
}
if (true) {
vector<int> v = st.sum(i, j, n, m);
ans = max(ans, (a[i][j] + i + j) - v[3] - 1);
}
}
}
cout << ans << '\n';
}
return 0;
}
