#include <bits/stdc++.h>
#include <experimental/random>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
void solve1();
using ll = long long;
using ull = unsigned long long;
using ld = double;
using BIG = __int128_t;
# define int long long
const int MOD = 1e9 + 7;
const int INF = 1e18;
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int qwerty = 1;
// cin >> qwerty;
while (qwerty--) {
solve1();
}
}
int dist(int a, int b) {
return abs(a - b);
}
int get(vector<vector<int>> &a, vector<vector<int>> &color, int c) {
int mn = INF, mx = -INF;
for (int i = 0; i < a.size(); i++) {
for (int j = 0; j < a[i].size(); j++) {
if (color[i][j] == c) {
mn = min(mn, a[i][j]);
mx = max(mx, a[i][j]);
}
}
}
if (mx == -INF) return 0;
return mx - mn;
}
void go_next(vector<vector<int>> &a) {
int n = a.size();
int m = a[0].size();
vector<vector<int>> b(m, vector<int>(n));
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
b[j][n - i - 1] = a[i][j];
}
}
a = b;
}
bool check(vector<vector<int>> &a, int x) {
bool flag = false;
for (int ZZZ = 0; ZZZ < 4; ZZZ++) {
int n = a.size();
int m = a[0].size();
int mx = 0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
mx = max(mx, a[i][j]);
}
}
vector<vector<int>> color(n, vector<int>(m, 2));
int mn_i = m - 1;
for (int i = 0; i < n; i++) {
int now = -1;
for (int j = 0; j <= mn_i; j++) {
if (mx - a[i][j] > x) break;
color[i][j] = 1;
now = j;
}
mn_i = now;
}
int f = get(a, color, 1);
int s = get(a, color, 2);
if (max(f, s) <= x) {
flag = true;
}
go_next(a);
}
return flag;
}
void solve1() {
int n, m;
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 l = -1, r = INF;
while (r - l > 1) {
int mid = (l + r) / 2;
if (check(a, mid)) {
r = mid;
} else {
l = mid;
}
}
cout << r;
}
