#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int , int>
#define fi first
#define se second
#define FOR(i , l , r) for(int i = (l) ; i <= (r) ; i++)
#define FOD(i , r , l) for(int i = (r) ; i >= (l) ; i--)
const int N = 2e3 + 5;
const int INF = 1e9 + 5;
int a[N][N];
int b[N][N];
int h , w;
vector<int> mrotate = {1 , 2 , 3 , 4};
int mx_val;
bool check(int mid) {
int mx = w;
int mnblue = INF;
int mxblue = 0;
FOR(i , 1 , h) {
FOR(j , 1 , mx) {
if(mx_val - a[i][j] > mid) {
mx = j - 1;
break;
}
}
FOR(j , mx + 1 , w) {
mnblue = min(a[i][j] , mnblue);
mxblue = max(a[i][j] , mxblue);
}
}
if(mxblue - mnblue > mid) return false;
return true;
}
void solve () {
cin >> h >> w;
FOR(i , 1 , h) {
FOR(j , 1 , w) {
cin >> a[i][j];
mx_val = max(mx_val , a[i][j]);
}
}
int ans = INF;
for(auto kk : mrotate) {
int l = 0;
int r = INF;
while(l <= r) {
int mid = (l + r) / 2;
if(check(mid)) {
ans = min(ans , mid);
r = mid - 1;
}
else{
l = mid + 1;
}
}
int curr_h = h;
int curr_w = w;
swap(h , w);
FOR(i , 1 , curr_h) {
FOR(j , 1 , curr_w) {
b[j][curr_h - i + 1] = a[i][j];
}
}
FOR(i , 1 , h) {
FOR(j , 1 , w) {
a[i][j] = b[i][j];
}
}
}
cout << ans;
}
main () {
ios_base :: sync_with_stdio(false);
cin.tie(NULL);
solve();
return 0;
}
