#include <bits/stdc++.h>
using namespace std;
const int DIM = 2005;
int mat[DIM][DIM];
void revLin(int n, int m) {
for (int i = 1; i <= n / 2; ++i) {
for (int j = 1; j <= m; ++j) {
swap(mat[i][j], mat[n - i + 1][j]); } } }
void revCol(int n, int m) {
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m / 2; ++j) {
swap(mat[i][j], mat[i][m - j + 1]); } } }
bool check(int n, int m, int vl, int mn, int mx) {
int ps = 0;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) {
if (mat[i][j] < mx - vl) {
ps = max(ps, j); } }
for (int j = 1; j <= m; ++j) {
if (mat[i][j] > mn + vl and j <= ps) {
return false; } } }
return true; }
int solve(int n, int m, int mn, int mx) {
int le = 0, ri = mx - mn;
while (le <= ri) {
int md = (le + ri) / 2;
if (check(n, m, md, mn, mx)) {
ri = md - 1; }
else {
le = md + 1; } }
return le; }
int main(void) {
#ifdef HOME
freopen("joioi.in", "r", stdin);
freopen("joioi.out", "w", stdout);
#endif
int n, m, mn = 1000000000, mx = 0; cin >> n >> m;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) {
cin >> mat[i][j];
mn = min(mn, mat[i][j]); mx = max(mx, mat[i][j]); } }
int ans = 1000000000;
ans = min(ans, solve(n, m, mn, mx)); revLin(n, m);
ans = min(ans, solve(n, m, mn, mx)); revCol(n, m);
ans = min(ans, solve(n, m, mn, mx)); revLin(n, m);
ans = min(ans, solve(n, m, mn, mx)); revCol(n, m);
cout << ans << endl;
return 0; }
