// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
#ifdef ULVI
#include "debug.hpp"
#else
#define db(...)
#define dbv(v)
#define line()
#endif
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define ff first
#define ss second
#define enld endl
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair<ll,ll> pll;
const ll sz=2e5+100;
const ll lg=20;
const ll mod=1e9+7;
const ll inf=1e18;
template<class T>
using indexed_set=tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
void solve(){
ll n,m;
cin>>n>>m;
vector<vector<ll>> v(n+5,vector<ll>(m+5));
for(ll i=1;i<=n;i++){
for(ll j=1;j<=m;j++) cin>>v[i][j];
}
ll ans=-inf;
for(ll i1=1;i1<=n;i1++){
for(ll j1=1;j1<=n;j1++){
for(ll i2=1;i2<=n;i2++){
for(ll j2=1;j2<=n;j2++){
ans=max(ans,v[i2][j2]-v[i1][j1]-(abs(i1-i2)+abs(j1-j2)));
}
}
}
}
cout<<ans<<'\n';
}
int main(){
// freopen("input.txt","r",stdin);
// freopen("output.txt","w",stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
ll t=1;
// cin>>t;
for(ll _=1;_<=t;_++){
// cout<<"Scenario #"<<_<<":\n";
solve();
}
}
