// #pragma comment(linker, "\stack:200000000")
// #pragma GCC optimize("Ofast")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcount,abm,mmx,avx,avx2,tune=native")
//#pragma GCC target("avx,avx2")
// #pragma GCC target("avx,avx2,fma")
// #pragma GCC optimization("O3")
// #pragma GCC optimization("unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define pb push_back
#define fi first
#define se second
#define pii pair<int, int>
#define pll pair<ll, ll>
using namespace std;
using namespace __gnu_pbds;
typedef
tree<
ll,
null_type,
less_equal<ll>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
const int N = 1e3 + 10;
const int mod = 1e9 + 7;
const ll INF = 1e16;
const int lim = 450;
int n, m, a[N][N];
int main() {
// ios_base::sync_with_stdio(NULL); cin.tie(NULL); cout.tie(NULL);
// freopen("input.txt", "r", stdin);
// freopen("input.in", "r", stdin);
// freopen("input.out", "w", stdout);
cin >> n >> m;
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 i1 = 1; i1 <= n; i1++)
for (int j1 = 1; j1 <= m; j1++)
ans = max(ans, max(a[i][j], a[i1][j1]) - min(a[i][j], a[i1][j1]) - abs(i - i1) - abs(j - j1) - 1);
cout << ans;
}
