/*
VENI VIDI VICI
*/
// #pragma GCC optimize("Ofast","unroll-all-loops","fast-math","no-stack-protector","give-no-*****")
#include <bits/stdc++.h>
// #include <iostream>
// #include <vector>
// #include <algorithm>
// #include <set>
// #include <map>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define rep(i,x, n) for (int i = (x); i < (n); ++i)
#define repr(i,x, n) for (int i = (n) - 1; i >= (x); --i)
mt19937 RNG(chrono::steady_clock::now().time_since_epoch().count());
// #define sum accumulate
//using i128 = __int128;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using str = string;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vpi = vector<pair<int, int>>;
using vvi = vector<vi>;
using sll = set<ll>;
template<class T>
istream& operator>>(istream& is, vector<T>& v) {
for(auto &i:v) is>>i;
return is;
}
template<class T1,class T2>
istream& operator>>(istream& is, pair<T1,T2>& p) {
is>>p.fi>>p.se;
return is;
}
template<class T>
ostream& operator<<(ostream& os, const vector<T>& v) {
for(const auto &i:v) os<<i<<' ';
return os;
}
template<class T1,class T2>
ostream& operator<<(ostream& os, const pair<T1,T2>& p) {
os<<p.fi<<' '<<p.se; return os;
}
void pyn(bool x)
{
cout<<(x?"YES":"NO")<<endl;
}
void pYN(bool x)
{
cout<<(x?"Yes":"No")<<endl;
}
void pAB(bool x)
{
cout<<(x?"Alice":"Bob")<<endl;
}
ll powmod(ll a,ll b,ll modulo)
{
if(b==0){
return 1;
}
ll temp=powmod(a,b/2,modulo);
if(b%2==0){
return (temp*temp)%modulo;
}
else{
return (a*((temp*temp)%modulo))%modulo;
}
}
bool Prime(ll n){
for (ll i = 2; i*i <= n; i++)
if (n % i == 0)
return false;
return (n>1);
}
void readIO() {
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
}
void solve();
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
// readIO();
int uwu=1;
// cin>>uwu;
for(int tc=1;tc<=uwu;tc++) {
// cout<<"Case #"<<tc<<": ";
solve();
}
return 0;
}
const int N=2e3+1;
int g[N][N],n,m,col[N],spf[N][N];
pair<int,int> pre[N][N],suf[N][N];
int getval()
{
vector<vector<int>> ord(n*m);
for(int i=0;i<n;i++)
{
col[i]=0;
for(int j=0;j<m;j++)
{
ord[i*m+j]={g[i][j],i,j};
pre[i][j]={g[i][j],g[i][j]};
if(j)
{
pre[i][j].first=min(pre[i][j].first,pre[i][j-1].first);
pre[i][j].second=max(pre[i][j].second,pre[i][j-1].second);
}
}
for(int j=m-1;j>=0;j--)
{
suf[i][j]={g[i][j],g[i][j]};
if(j<m-1)
{
suf[i][j].first=min(suf[i][j].first,suf[i][j+1].first);
suf[i][j].second=max(suf[i][j].second,suf[i][j+1].second);
}
}
}
sort(all(ord));
int ans=2e9;
for(auto tlp:ord)
// for(int i=0;i<n;i++)
{
int i=tlp[1],j=tlp[2];
{ // fix this as maximum
for(int r=0;r<n and (r==0 or col[r]<col[r-1]);r++)
{
for(;(r==0 and col[r]<m) or (r>0 and col[r]<col[r-1]);)
{
if(g[r][col[r]]<=g[i][j])
{
col[r]++;
}
else
{
break;
}
}
}
if(col[i]>j)
{
int mx=-2e9,mi=2e9;
int mx2=-2e9,mi2=2e9;
int mip=m;
for(int r=0;r<n;r++){
mip=min(mip,col[r]);
if(mip>0)
{
mx=max(mx,pre[r][mip-1].second);
mi=min(mi,pre[r][mip-1].first);
}
if(mip<m)
{
mx2=max(mx2,suf[r][mip].second);
mi2=min(mi2,suf[r][mip].first);
}
}
if(mx!=-2e9 and mx2!=-2e9)
ans=min(ans,max(mx2-mi2,mx-mi));
}
}
}
return ans;
}
void rotate()
{
for(int i=0;i<n;i++)
{
for(int j=0;j<m;j++)
{
spf[i][j]=g[i][j];
}
}
swap(n,m);
for(int i=0;i<n;i++)
{
for(int j=0;j<m;j++)
{
g[i][j]=spf[j][i];
}
}
for(int i=0;i<n;i++)
{
reverse(g[i],g[i]+m);
}
}
void solve()
{
cin>>n>>m;
for(int i=0;i<n;i++)
{
for(int j=0;j<m;j++)
{
cin>>g[i][j];
}
}
int cur=2e9;
for(int i=0;i<4;i++)
{
rotate();
cur=min(cur,getval());
}
cout<<cur<<endl;
}
