#define _CRT_SECURE_NO_WARNINGS
#ifdef KEK
#define FILE_IN "input.txt"
#define FILE_OUT "output.txt"
#endif
#include <iostream>
#include <cstdlib>
#include <climits>
#include <set>
#include <map>
#include <cstdio>
#include <string>
#include <cstring>
#include <cassert>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;
typedef long long ll;
void openFiles() {
#ifdef KEK
assert(freopen(FILE_IN, "r", stdin));
assert(freopen(FILE_OUT, "w", stdout));
#endif
}
const int MAXH = 12;
const int INF = INT_MAX;
int a[MAXH][MAXH];
int x[MAXH];
int h, w;
int ans = INF;
void solve() {
memset(x, 0, sizeof(x));
x[w - 1] = 1;
while (true) {
int mx[2] = {-INF, -INF};
int mn[2] = {INF, INF};
bool need_stop = true;
for (int i = 0; i < w; i++) {
//cout << x[i] << " ";
if (x[i] != h)
need_stop = false;
}
//cout << "\n";
if (need_stop)
break;
for (int i = 0; i < h; i++) {
for (int j = 0; j < w; j++) {
int type = (x[j] > i);
mx[type] = max(mx[type], a[i][j]);
mn[type] = min(mn[type], a[i][j]);
}
}
int res1 = mx[0] - mn[0];
int res2 = mx[1] - mn[1];
int new_ans = max(res1, res2);
//cout << new_ans << "\n";
ans = min(ans, new_ans);
x[w - 1]++;
int pos = w - 1;
while (pos > 0 && x[pos] == h + 1) {
x[pos - 1]++;
for (int i = pos; i < w; i++) {
x[i] = x[pos - 1];
}
pos--;
}
if (x[0] == h + 1) {
break;
}
}
}
void magic() {
for (int i = 0; i < h; i++) {
for (int j = 0; 2 * j < w; j++) {
swap(a[i][j], a[i][w - j - 1]);
}
}
}
int main() {
openFiles();
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> h >> w;
for (int i = 0; i < h; i++) {
for (int j = 0; j < w; j++) {
cin >> a[i][j];
}
}
solve();
magic();
solve();
cout << ans;
return 0;
}
