#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
using namespace std;
#define int long long int
const int N = 1e3 + 1;
const int md = 1e9 + 7;
const int INF = 1e9 + 5000;
int n, m;
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> {INF, -INF, INF, -INF}));
}
void update_y(int cx, int lx, int rx, int cy, int ly, int ry, int x, int y, int val) {
if (ry - ly == 1) {
if (rx - lx == 1) {
tree[cx][cy] = {val - lx - ly, val + lx + ly, val - lx + ly, val + lx - ly};
} else {
for (int i = 0; i < 4; i++) {
tree[cx][cy][i] = (i % 2 == 0) ? min(tree[2 * cx + 1][cy][i], tree[2 * cx + 2][cy][i]) :
max(tree[2 * cx + 1][cy][i], tree[2 * cx + 2][cy][i]);
}
}
} else {
int m = (ly + ry) >> 1;
if (y < m)
update_y(cx, lx, rx, 2 * cy + 1, ly, m, x, y, val);
else
update_y(cx, lx, rx, 2 * cy + 2, m, ry, x, y, val);
for (int i = 0; i < 4; i++) {
tree[cx][cy][i] = (i % 2 == 0) ? min(tree[cx][2 * cy + 1][i], tree[cx][2 * cy + 2][i]) :
max(tree[cx][2 * cy + 1][i], tree[cx][2 * cy + 2][i]);
}
}
}
void update_x(int cx, int lx, int rx, int x, int y, int val) {
if (rx - lx == 1) {
update_y(cx, lx, rx, 0, 0, size_m, x, y, val);
} else {
int m = (lx + rx) >> 1;
if (x < m)
update_x(cx * 2 + 1, lx, m, x, y, val);
else
update_x(cx * 2 + 2, m, rx, x, y, val);
update_y(cx, lx, rx, 0, 0, size_m, x, y, val);
}
}
void update(int x, int y, int val) {
update_x(0, 0, size_n, x, y, val);
return;
}
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;
auto v = sum_y(cx ,cy * 2 + 1 ,tly ,try_ ,ly ,m);
auto v1 = sum_y(cx ,cy * 2 + 2 ,tly ,try_ ,m ,ry);
return {min(v[0], v1[0]), max(v[1], v1[1]), min(v[2], v1[2]), max(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;
auto v = sum_x(cx * 2 + 1 ,tlx ,trx ,lx ,m ,ly ,ry);
auto v1 = sum_x(cx * 2 + 2 ,tlx ,trx ,m ,rx ,ly ,ry);
return {min(v[0], v1[0]), max(v[1], v1[1]), min(v[2], v1[2]), max(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() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m;
segtree st;
st.init(n,m);
int ans = -1;
for (int i = 0; i < n; i++)
for (int j = 0; j < m; j++) {
int x;
cin >> x;
st.update(i,j,x);
auto v_sum_ij = st.sum(0 ,0,i+1,j+1);
ans = max(ans,(x-i-j)-v_sum_ij[0]-1);
ans = max(ans,v_sum_ij[1]-(x+i+j)-1);
auto v_sum_j_full = st.sum(0,j,i+1,m);
ans = max(ans,(x-i+j)-v_sum_j_full[2]-1);
ans = max(ans,v_sum_j_full[3]-(x+i-j)-1);
}
cout << ans << '\n';
return 0;
}
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