#include <iostream>
#include <iomanip>
#include <cstdio>
#include <vector>
#include <bitset>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <utility>
#include <algorithm>
#include <random>
#include <cmath>
#include <cassert>
#include <climits>
#include <ctime>
#include <chrono>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx,avx2,tune=native")
#ifdef LOCAL
#define dbg(x) cout << #x << " : " << x << endl;
#else
#define dbg(x)
#endif
#define pb push_back
#define ppb pop_back()
#define mp make_pair
#define fi(a, b) for (int i = a; i < b; i++)
#define fj(a, b) for (int j = a; j < b; j++)
#define fk(a, b) for (int k = a; k < b; k++)
#define fi1(a, b) for (int i = a - 1; i >= b; i--)
#define fj1(a, b) for (int j = a - 1; j >= b; j--)
#define fk1(a, b) for (int k = a - 1; k >= b; k--)
#define fx(x, a) for (auto& x : a)
#define rep(i, a, b) for (int i = a; i < b; ++i)
#define rep1(i, a, b) for (int i = a - 1; i >= b; --i)
#define siz(x) (int)x.size()
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
using namespace std;
template<typename T1, typename T2>inline void mine(T1 &x, const T2 &y) { if (y < x) x = y; }
template<typename T1, typename T2>inline void maxe(T1 &x, const T2 &y) { if (x < y) x = y; }
ostream& operator << (ostream &out, const vector<int> &b) {
for (auto k : b) out << k << ' ';
return out;
}
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef char ch;
typedef string str;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef vector<vpii> vvpii;
typedef vector<ch> vch;
typedef vector<vch> vvch;
typedef vector<str> vs;
const int MOD = 1000000007;
const int INF = 1000000050;
const long long BIG = (long long)2e18 + 50;
const int MX = 2010;
const double EPS = 1e-9;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n, m;
int a[MX][MX];
int sm[MX];
int pm[MX];
int mni;
int mnj;
int mxi;
int mxj;
bool check(int x) {
int ok = a[mni][mnj] + x;
fj(0, m) {
pm[j] = (j ? pm[j - 1] : n);
fi(0, pm[j]) {
if (a[i][j] > ok) {
pm[j] = i;
break;
}
}
}
fj1(m, 0) {
sm[j] = (j < m - 1 ? sm[j + 1] : n);
fi(0, sm[j]) {
if (a[i][j] > ok) {
sm[j] = i;
break;
}
}
}
int ok2 = a[mxi][mxj] - x;
if (sm[mnj] > mni) {
bool nice = true;
for (int j = 0; j < m && nice; ++j) {
for (int i = sm[j]; i < n && nice; ++i) {
nice &= a[i][j] >= ok2;
}
}
if (nice) return true;
}
if (pm[mnj] > mni) {
bool nice = true;
for (int j = 0; j < m && nice; ++j) {
for (int i = pm[j]; i < n && nice; ++i) {
nice &= a[i][j] >= ok2;
}
}
if (nice) return true;
}
return false;
}
int ans = INF;
void solve() {
mxi = mxj = mni = mnj = 0;
fi(0, n) {
fj(0, m) {
if (a[i][j] < a[mni][mnj]) {
mni = i;
mnj = j;
}
if (a[i][j] > a[mxi][mxj]) {
mxi = i;
mxj = j;
}
}
}
int L = -1;
int R = a[mxi][mxj] - a[mni][mnj];
while (R - L > 1) {
int x = (R + L) / 2;
if (check(x))
R = x;
else
L = x;
}
mine(ans, R);
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> m;
fi(0, n) fj(0, m) cin >> a[i][j];
solve();
fi(0, n) fj(0, m) a[i][j] *= -1;
solve();
cout << ans << '\n';
}
