#include<bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0); cin.tie(0)
#define F first
#define S second
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
template<class T>
using vvector = vector<vector<T>>;
const int INF = 0x3f3f3f3f;
bool check(int w,int h,int d,vector<pll> &rg1,vector<pll> &rg2) {
}
bool ok(int h,int w,vvector<ll> &a,int mn,int mx,ll x) {
vector<pll> rg1(h+1,{INF,0}),rg2(h+1,{INF,0});
for (int i=1;i<=h;i++) {
for (ll j=1;j<=w;j++) {
if (a[i][j]>mn+x) {
rg2[i].F=min(j,rg2[i].F);
rg2[i].S=max(j,rg2[i].S);
}
if (a[i][j]<mx-x) {
rg1[i].F=min(j,rg1[i].F);
rg1[i].S=max(j,rg1[i].S);
}
}
if (!(rg1[i].S<rg2[i].F or rg2[i].S<rg1[i].F)) return false;
}
bool flagd1=true;
ll now=w;
for (int i=1;i<=h;i++) {
now=min(now,rg2[i].F-1);
if (now<rg1[i].S) {
flagd1=false;
break;
}
}
bool flagd2=true;
now=w;
for (int i=1;i<=h;i++) {
now=min(now,rg1[i].F-1);
if (now<rg2[i].S) {
flagd2=false;
break;
}
}
// cout<<flagd<<" fd\n";
bool flaga1=true;
now=0;
for (int i=1;i<=h;i++) {
now=max(now,rg1[i].S);
if (rg2[i].F<=now) {
flaga1=false;
break;
}
}
bool flaga2=true;
now=0;
for (int i=1;i<=h;i++) {
now=max(now,rg2[i].S);
if (rg1[i].F<=now) {
flaga2=false;
break;
}
}
// cout<<flaga<<" fa\n";
return flaga1 or flagd1 or flaga2 or flagd2;
}
int main() {
speed;
ll h,w;
cin>>h>>w;
vvector<ll> a(h+1,vector<ll>(w+1));
ll mn=INF,mx=0;
for (int i=1;i<=h;i++) {
for (int j=1;j<=w;j++) {
cin>>a[i][j];
mx=max(mx,a[i][j]);
mn=min(mn,a[i][j]);
}
}
ll l=0,r=INF;
while (l<r) {
int mid=l+r>>1;
if (ok(h,w,a,mn,mx,mid)) r=mid;
else l=mid+1;
}
cout<<l<<"\n";
return 0;
}
/*
4 4
1 1 1 1
5 5 5 5
1 1 1 1
1 1 1 1
*/
