// #pragma GCC optimize("O3")
// #pragma GCC optimization("Ofast,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ll long long
#define FOR(i, l, r) for (int i = (l); i <= (r); i++)
#define FOD(i, r, l) for (int i = (r); i >= (l); i--)
#define fi first
#define se second
#define pii pair<int, int>
const ll mod = 1e9 + 7;
const int MAXN = 2e3 + 5;
const ll oo = 1e18 + 7;
const int base = 10;
int m, n, a[MAXN][MAXN], mi=oo;
int hx[]={-1, 1, 0, 0}, hy[]={0, 0, -1, 1};
int f[MAXN][MAXN];
int ps[MAXN][MAXN];
int b[MAXN][MAXN];
bool chk(int k){
FOR(i, 1, m){
FOR(j, 1, n){
f[i][j]=0;
// cout << b[i][j] << ' ';
}
// cout << '\n';
}
int last=oo;
FOR(i, 1, m){
int pos=last;
FOR(j, 1, n){
if(b[i][j]-mi>k){
pos=j;
break;
}
}
pos=min(pos, last);
last=pos;
FOR(j, pos, n){
f[i][j]=1;
}
}
int mi0=oo, mx0=-oo, mi1=oo, mx1=-oo;
FOR(i, 1, m){
FOR(j, 1, n){
if(f[i][j]==0){
mi0=min(mi0, b[i][j]);
mx0=max(mx0, b[i][j]);
}
else{
mi1=min(mi1, b[i][j]);
mx1=max(mx1, b[i][j]);
}
}
}
return (mx0-mi0<=k && mx1-mi1<=k);
}
bool check(int k){
FOR(i, 1, m){
FOR(j, 1, n){
b[i][j]=a[i][j];
}
}
if(chk(k)) return 1;
FOR(i, 1, m){
FOR(j, 1, n){
b[i][j]=a[i][n-j+1];
}
}
if(chk(k)) return 1;
FOR(i, 1, m){
FOR(j, 1, n){
b[i][j]=a[m-i+1][j];
}
}
if(chk(k)) return 1;
FOR(i, 1, m){
FOR(j, 1, n){
b[i][j]=a[m-i+1][n-j+1];
}
}
if(chk(k)) return 1;
return 0;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
// freopen("test.txt", "r", stdin);
// freopen("o2.out", "w", stdout);
if(fopen(".inp", "r")){
freopen(".inp", "r", stdin);
freopen(".out", "w", stdout);
}
cin >> m >> n;
FOR(i, 1, m){
FOR(j, 1, n){
cin >> a[i][j];
mi=min(mi, a[i][j]);
}
}
// cout << check(18) << '\n';
// cout << check(17);
int l=0, r=1e9, ans=0;
while(l<=r){
int mid=(l+r)/2;
if(check(mid)){
ans=mid;
r=mid-1;
}
else{
l=mid+1;
}
}
cout << ans;
return 0;
}
