// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
using namespace std;
#define int long long
#define endl "\n"
#define fi first
#define se second
const int M=1e9+7;
const int inf = 1e15;
const int LOG=17;
const int N=2e5+5;
int n , m , c , w , k , t=1 , q=1 , x , y , z , l , r;
void solve(){
cin >> n >> m;
vector<vector<int>>a(n,vector<int>(m));
for (int i=0;i<n;i++){
for (int j=0;j<m;j++){
cin >> a[i][j];
}
}
int ans=-1;
for (int i=0;i<n;i++){
for (int j=0;j<m;j++){
for (int i1=0;i1<n;i1++){
for (int j1=0;j1<m;j1++){
ans=max(ans,abs(a[i][j]-a[i1][j1])-(abs(i-i1)+abs(j-j1)+1));
}
}
}
}
cout << ans << endl;
}
signed main()
{
ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
cin.tie(0), cout.tie(0);//DO NOT USE IN INTERACTIVE
cout << fixed << setprecision(9);
srand(time(0));
// int t=1;
// cin >> t;
for (int _=1;_<=t;_++){
solve();
q++;
}
}
