#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll mod = 1e9 + 7;
ll inf = 2000000000;
int main() {
ll n, m;
cin >> n >> m;
vector<vector<ll>>matrica(n, vector<ll>(m));
ll maks = -10;
ll maksmin = -10;
ll najdi, najdj, najdi1, najdj1;
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < m; j++) {
cin >> matrica[i][j];
if (maks < matrica[i][j] - matrica[0][0] - i - j - 1) {
maks = matrica[i][j] - matrica[0][0] - i - j - 1;
najdi = i;
najdj = j;
}
if (maksmin < matrica[0][0] - matrica[i][j] - i - j - 1) {
maksmin = matrica[0][0] - matrica[i][j] - i - j - 1;
najdi1 = i;
najdj1 = j;
}
}
}
// cout << najdi << " " << najdj << endl;
ll maks2 = -10, maks3 = -10;
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < m; j++) {
maks2 = max(maks2, abs(matrica[i][j] - matrica[najdi][najdj]) - abs(najdi - i) - abs(j - najdj) - 1);
maks3 = max(maks2, abs(matrica[i][j] - matrica[najdi1][najdj1]) - abs(najdi1 - i) - abs(j - najdj1) - 1);
}
}
cout << max(maks2, maks3) << endl;
}
