#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define pb push_back
#define pf push_front
#define mp make_pair
#define ll long long
int grid[2000][2000], h, w, maxnum = 0, minnum = INT_MAX;
bool visited[2000][2000];
void rotate() {
vector<vector<int>> copygrid(2000, vector<int>(2000));
for (int i=0;i<h;i++) {
for (int j=0;j<w;j++) {
copygrid[w - j - 1][i] = grid[i][j];
}
}
swap(h, w);
for (int i=0;i<h;i++) {
for (int j=0;j<w;j++) {
grid[i][j] = copygrid[i][j];
}
}
}
bool anscheck(int a) {
if (maxnum - minnum <= a) return true;
for (int _=0;_<4;_++) {
bool ans = true;
for (int i=0;i<h;i++) {
for (int j=0;j<w;j++) {
visited[i][j] = false;
}
}
int maxcol = w;
for (int i=0;i<h;i++) {
for (int j=0;j<maxcol;j++) {
if (maxnum - grid[i][j] > a) {
maxcol = j;
} else visited[i][j] = true;
}
}
for (int i=0;i<h;i++) {
for (int j=0;j<w;j++) {
if (!visited[i][j] && grid[i][j] - minnum > a) {
ans = false; break;
}
}
}
if (ans) return true;
ans = true;
for (int i=0;i<h;i++) {
for (int j=0;j<w;j++) {
visited[i][j] = false;
}
}
int mincol = -1;
for (int i=0;i<h;i++) {
for (int j=w-1;j>mincol;j--) {
if (maxnum - grid[i][j] > a) {
mincol = j;
} else visited[i][j] = true;
}
}
for (int i=0;i<h;i++) {
for (int j=0;j<w;j++) {
if (!visited[i][j] && grid[i][j] - minnum > a) {
ans = false; break;
}
}
}
if (ans) return true;
rotate();
}
return false;
}
int main() {
cin >> h >> w;
for (int i=0;i<h;i++) {
for (int j=0;j<w;j++) {
cin >> grid[i][j];
maxnum = max(maxnum, grid[i][j]);
minnum = min(minnum, grid[i][j]);
}
}
int top = 1000000000, bottom = -1, mid;
while (top > bottom + 1) {
mid = (top + bottom) / 2;
if (anscheck(mid)) top = mid;
else bottom = mid;
}
cout << top;
}
