#include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <algorithm>
#include <set>
#include <queue>
#include <map>
#include <stack>
#include <bitset>
#include <string>
#include <cstring>
#include <iterator>
#include <random>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
const ll dim = 5*1e3+7;
//const ll mod = 1e9 + 7;
const ll inf = 1e18 + 77;
#define endl "\n"
#define fi first
#define pb push_back
#define se second
#define vll vector<ll>
ll n, m;
ll fl[dim];
ll mx, mn;
ll check(ll val, vector<vll> &a){
ll mnv=mx-val;
ll mxv=mn+val;
// cout<<mnv<<" "<<mxv<<" "<<val<<endl;
ll can1=1;
ll can2=1;
ll end=n+1;
for(int j=m; j>=1; j--){
for(int i=1; i<=end; i++){
if(a[i][j]>mxv){end=i; break;}
}
fl[j]=end;
}
for(int j=1; j<=m; j++){
for(int i=n; i>=max(fl[j], 1ll); i--){
if(a[i][j]<mnv)can1=0;
}
for(int i=1; i<fl[j]; i++){
if(a[i][j]>mxv)can1=0;
}
fl[j]=0;
}
end=n+1;
for(int j=1; j<=m; j++){
for(int i=1; i<=end; i++){
if(a[i][j]>mxv){end=i; break;}
}
fl[j]=end;
}
for(int j=1; j<=m; j++){
for(int i=n; i>=max(fl[j], 1ll); i--){
if(a[i][j]<mnv)can2=0;
}
for(int i=1; i<fl[j]; i++){
if(a[i][j]>mxv)can2=0;
}
fl[j]=0;
}
if(can1 || can2)return 1;
return 0;
}
int main() {
ll d, k, q, s, t, e, sm;
cin>>n>>m;
mx=0;
mn=inf;
vector<vll> g(n+5, vll(m+5, 0));
vector<vll> b(n+5, vll(m+5, 0));
for(int i=1;i<=n; i++){
for(int j=1; j<=m; j++){
cin>>g[i][j];
mx=max(g[i][j], mx);
mn=min(g[i][j], mn);
}
}
for(int i=1; i<=n; i++){
for(int j=1; j<=m; j++){
b[i][j]=g[n-i+1][j];
}
}
ll l=1;
ll r=1e9;
while(r-l>=1){
ll mid=(l+r)/2;
if(check(mid, g)|| check(mid, b)){
r=mid;
}
else{
l=mid+1;
}
}
cout<<l<<endl;
return 0;
}
