#include <bits/stdc++.h>
#define ar array
//#define int long long
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int mod = 1e9 + 7;
const ll inf = 1e18;
const int N = 1e5 + 5;
signed main() {
int n, m; cin >> n >> m;
vector<vector<int> > a(n+1, vector<int>(m+1));
for(int i=1; i<=n; i++)
for(int j=1; j<=m; j++) cin >> a[i][j];
int ans = -1;
for(int i=1; i<=n; i++) {
for(int j=1; j<=m; j++) {
for(int k=1; k<=n; k++) {
for(int l=1; l<=m; l++) {
ans = max(ans, abs(a[i][j] - a[k][l]) - abs(i-k) - abs(j-l) - 1);
}
}
}
}
cout << ans << '\n';
}
