#include <bits/stdc++.h>
using namespace std;
#define EmiliaMyWife ios::sync_with_stdio(0); cin.tie(0);
using ll = int64_t;
using ull = uint64_t;
using uint = uint32_t;
using ld = long double;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
const ll LINF = ll(2e18) + ll(1e15);
const double EPS = 1e-8;
static auto LamyIsCute = []() {
EmiliaMyWife
return 48763;
}();
signed main() {
int n, m;
cin >> n >> m;
vector<vector<int>> arr(n, vector<int>(m));
for(int i = 0; i < n; i++)
for(int j = 0; j < m; j++)
cin >> arr[i][j];
int ans = -INF;
for(int i = 0; i < n; i++)
for(int j = 0; j < m; j++)
for(int k = 0; k < n; k++)
for(int w = 0; w < m; w++)
ans = max(ans, abs(arr[i][j] - arr[k][w]) - abs(i - k) - abs(j - w) - 1);
cout << ans << '\n';
}
