// Source: https://usaco.guide/general/io
#include <bits/stdc++.h>
using namespace std;
int n, m, a[1005][1005], b[1005][1005], c[1005][1005], d[1005][1005], e[1005][1005];
int main() {
cin >> n >> m;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) cin >> a[i][j];
}
for (int i = 1; i <= n; i++) {
b[i][0] = 2e9;
c[i][m + 1] = 2e9;
d[i][0] = 2e9;
e[i][m + 1] = 2e9;
}
for (int i = 1; i <= m; i++) b[0][i] = c[0][i] = 2e9, d[n + 1][i] = e[n + 1][i] = 2e9;
int ans = 0;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
ans = max(ans, a[i][j] - i - j - min(b[i][j - 1], b[i - 1][j]));
b[i][j] = min({b[i - 1][j], b[i][j - 1], a[i][j] - i - j});
}
}
for (int i = 1; i <= n; i++) {
for (int j = m; j >= 1; j--) {
ans = max(ans, a[i][j] - i + j - min(c[i][j + 1], c[i - 1][j]));
c[i][j] = min({c[i - 1][j], c[i][j + 1], a[i][j] - i + j});
}
}
for (int i = n; i >= 1; i--) {
for (int j = 1; j <= m; j++) {
ans = max(ans, a[i][j] + i - j - min(d[i][j - 1], d[i + 1][j]));
d[i][j] = min({d[i + 1][j], d[i][j - 1], a[i][j] + i - j});
}
}
for (int i = n; i >= 1; i--) {
for (int j = m; j >= 1; j--) {
ans = max(ans, a[i][j] + i + j - min(e[i][j + 1], e[i + 1][j]));
e[i][j] = min({e[i + 1][j], e[i][j + 1], a[i][j] + i + j});
}
}
cout << ans - 1;
}
