#include <iostream>
using namespace std;
const int MAXN = 501;
int n, m;
int tablica[MAXN][MAXN];
int p1[MAXN][MAXN];
int wynik = 1000000000;
int min_ele = 1000000000;
void obroc() {
for (int i = 0; n > i; i++) {
for (int j = 0; m > j; j++) {
p1[m - 1 - j][i] = tablica[i][j];
}
}
for (int i = 0; n > i; i++) {
for (int j = 0; m > j; j++) {
tablica[m - 1 -j][i] = p1[m - 1 - j][i];
}
}
swap(m, n);
}
bool BS(int val) {
int aktl_koniec = 1000000000;
int p1;
int max_r = -1000000000, min_r = 1000000000;
for (int i = 0; n > i; i++) {
p1 = -1;
while (((p1 + 1) < m) && (tablica[i][p1 + 1] - min_ele) <= val && (aktl_koniec >= p1 + 1)) {
p1++;
}
aktl_koniec = p1;
for (int j = (p1 + 1); m > j; j++) {
max_r = max(max_r, tablica[i][j]);
min_r = min(min_r, tablica[i][j]);
}
}
if ((max_r - min_r) <= val) {
return true;
}
return false;
}
int zrob_BS() {
int l = 0, r = 1000000, mid;
while (r > l) {
mid = (l + r)/2;
if (BS(mid)) {
r = mid;
} else {
l = mid + 1;
}
}
return r;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for (int i = 0; n > i; i++) {
for (int j = 0; m > j; j++) {
cin >> tablica[i][j];
min_ele = min(min_ele, tablica[i][j]);
}
}
wynik = zrob_BS();
for (int i = 0; 3 > i; i++) {
obroc();
wynik = min(wynik, zrob_BS());
}
cout << wynik;
return 0;
}
