#include <iostream>
using namespace std;
int a[2005][2005], Max;
bool poss(int n, int m, int k){
int mx = -1, mn = 1e9, id = 0;
for (int j=m;j>=1;j--){
int ind = n;
while (ind > id and Max - a[ind][j] <= k)
ind--;
id = ind;
while (ind > 0)
mx = max(mx, a[ind][j]), mn = min(mn, a[ind][j]), ind--;
}
return (mx == -1 or mx - mn <= k);
}
int getMin(int n, int m){
int l = -1, r = 1e9 + 7;
while (l + 1 < r){
int mid = (l + r) / 2;
if (poss(n, m, mid))
r = mid;
else
l = mid;
}
return r;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int n, m, Mn;
cin>>n>>m;
for (int i=1;i<=n;i++){
for (int j=1;j<=m;j++)
cin>>a[i][j], Max = max(Max, a[i][j]);
}
Mn = getMin(n, m);
for (int i=1;i<=n;i++){
for (int j=1;j+j<=m;j++)
swap(a[i][j], a[i][m - j + 1]);
}
Mn = min(Mn, getMin(n, m));
for (int i=1;i + i <= n;i++){
for (int j=1;j<=m;j++)
swap(a[i][j], a[n - i + 1][j]);
}
Mn = min(Mn, getMin(n, m));
for (int i=1;i<=n;i++){
for (int j=1;j+j<=m;j++)
swap(a[i][j], a[i][m - j + 1]);
}
Mn = min(Mn, getMin(n, m));
cout<<Mn<<'\n';
}
