#include<bits/stdc++.h>
#define ll long long
#define int long long
#define maxn 2005
#define fi first
#define se second
#define sti string
using namespace std;
ll a[maxn][maxn],b[maxn][maxn];
ll H,W,Min=4e18,Max=-4e18;
bool check(int Diff){
int firstI=0;
for(int i=1;i<=H;i++){
for(int j=1;j<=W;j++){
if(b[i][j] < Max-Diff){
firstI=max(firstI,j);
}
}
for(int j=1;j<=W;j++){
if(b[i][j] > Min+Diff){
if(j<=firstI) return 0;
}
}
}
return 1;
}
void flip_none() {
for (int i = 1; i <= H; i++)
for (int j = 1; j <= W; j++)
b[i][j] = a[i][j];
}
void flip_vertical() {
for (int i = 1; i <= H; i++)
for (int j = 1; j <= W; j++)
b[i][j] = a[H - i + 1][j];
}
void flip_horizontal() {
for (int i = 1; i <= H; i++)
for (int j = 1; j <= W; j++)
b[i][j] = a[i][W - j + 1];
}
void flip_both() {
for (int i = 1; i <= H; i++)
for (int j = 1; j <= W; j++)
b[i][j] = a[H - i + 1][W - j + 1];
}
bool ok(int D) {
flip_none();
if (check(D)) return 1;
flip_vertical();
if (check(D)) return 1;
flip_horizontal();
if (check(D)) return 1;
flip_both();
if (check(D)) return 1;
return 0;
}
signed main ()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>H>>W;
for(int i=1;i<=H;i++){
for(int j=1;j<=W;j++){
cin>>a[i][j];
Min=min(Min,a[i][j]);
Max=max(Max,a[i][j]);
}
}
ll L=0,R=Max-Min,ans=R;
while(L<=R){
ll mid=(L+R)/2;
if(ok(mid)){
ans=mid;
R=mid-1;
}
else L=mid+1;
}
cout<<ans;
return 0;
}
