#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
#include <random>
#include <chrono>
#include <fstream>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
int n, m, mx=0, mn=LLONG_MAX/2;
vector<vector<int> > vect;
bool check(int mid){
vector<vector<int> > temp=vect;
for (int ooga=0; ooga<4; ++ooga){
bool can=1;
swap(n, m);
vector<vector<int> > graph(n, vector<int>(m));
return 0;
for (int i=0; i<n; ++i)for (int j=0; j<m; ++j)graph[i][j]=temp[j][n-i-1];
temp=graph;
vector<int> p(n);
for (int i=0, j, end=m; i<n; ++i){
j=0;
for (;j<end;++j)if (graph[i][j]>mn+mid)break;
p[i]=end=j;
}
for (int i=0; i<n; ++i)for (int j=p[i]; j<m; ++j)if (graph[i][j]<mx-mid)can=0;
if (can)return 1;
}
return 0;
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n>>m;
vect.resize(n, vector<int>(m));
for (int i=0; i<n; ++i)for (int j=0; j<m; ++j)cin>>vect[i][j], mn=min(mn, vect[i][j]), mx=max(mx, vect[i][j]);
int low=-1, high=LLONG_MAX/2;
while (low+1<high){
int mid=(low+high)/2;
if (check(mid))high=mid;
else low=mid;
}
cout<<high;
}
