#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
int n, m, ans = -2;
int ar[3005][3005];
int val[3005][3005][4];
int mn[3005][3005][4];
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
cin >> ar[i][j];
val[i][j][0] = ar[i][j] - i - j + 1;
val[i][j][1] = ar[i][j] - m + j - i;
val[i][j][2] = ar[i][j] + i + j - 1;
val[i][j][3] = ar[i][j] + m - j + i;
}
}
memset(mn, 0x3f, sizeof mn);
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
mn[i][j][0] = min({val[i][j][0], mn[i - 1][j][0], mn[i][j - 1][0]});
ans = max(ans, val[i][j][0] - mn[i][j][0]);
}
}
for (int i = 1; i <= n; i++) {
for (int j = m; j >= 1; j--) {
mn[i][j][1] = min({val[i][j][1], mn[i - 1][j][1], mn[i][j + 1][1]});
ans = max(ans, val[i][j][1] - mn[i][j][1]);
}
}
for (int i = n; i >= 1; i--) {
for (int j = m; j >= 1; j--) {
mn[i][j][2] = min({val[i][j][2], mn[i + 1][j][2], mn[i][j + 1][2]});
ans = max(ans, val[i][j][2] - mn[i][j][2]);
}
}
for (int i = n; i >= 1; i--) {
for (int j = 1; j <= m; j++) {
mn[i][j][3] = min({val[i][j][3], mn[i + 1][j][3], mn[i][j - 1][3]});
ans = max(ans, val[i][j][3] - mn[i][j][3]);
}
}
cout << ans - 1 << '\n';
return 0;
}
