#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 = 0;
ll najdi, najdj;
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < m; j++) {
cin >> matrica[i][j];
// if (maks < (abs(matrica[i][j] - matrica[0][0]) - i - j - 1)) {
// maks = abs(matrica[i][j] - matrica[0][0]) - i - j - 1;
// najdi = i;
// najdj = j;
// }
}
}
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < m; j++) {
for (ll k = 0; k < n; k++) {
for (ll l = 0; l < m; l++) {
maks = max(maks, matrica[i][j] - matrica[k][l] - abs(i - k) - abs(j - l) - 1);
}
}
}
}
cout << maks << endl;
// cout << najdi << " " << najdj << endl;
// ll maks2 = 0;
// 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);
// }
// }
// cout << maks2 << endl;
}
