#include<bits/stdc++.h>
using namespace std;
const int inf = 1e9;
int n,m,pos[2005];
int a[2005][2005],ans = inf,mn = inf,mini[2005][2005],maxi[2005][2005],temp[2005][2005];
void _rotate(){
int numi=1,numj=1;
for(int i = 1 ; i <= m;i++){
for(int j = n;j >= 1;j--){
temp[numi][numj] = a[j][i];
numj++;
}
numj=1;
numi++;
}
swap(n,m);
for(int i = 1;i<=n;i++){
for(int j = 1;j<=m;j++)
a[i][j] = temp[i][j];
}
}
bool check(int val){
for(int i = 1;i <= n;i++){
pos[i] = m + 1;
for(int j = 1;j <= m;j++){
if(a[i][j] > mn + val){pos[i] = j; break;}
}
}
for(int i = 1;i <= n;i++){
mini[i][m+1] = inf;
maxi[i][m+1] = 1;
for(int j = m;j >= 1;j--){
mini[i][j] = min(a[i][j],mini[i][j+1]);
maxi[i][j] = max(a[i][j],maxi[i][j+1]);
}
mini[i][0] = mini[i][1]; maxi[i][0] = maxi[i][1];
}
int curMin = inf,curMax = 1,cur = m+1;
for(int i = 1;i <= n;i++){
cur = min(cur,pos[i]);
curMin = min(curMin,mini[i][cur]);
curMax = max(curMax,maxi[i][cur]);
}
if(curMax - curMin<=val)
return 1;
else
return 0;
}
void solve(){
int l = 0,r = inf - 1,mid;
while(l<r){
mid = (l+r)/2;
if(check(mid)) r = mid;
else l = mid+1;
}
ans = min(ans,l);
}
int main(){
cin.tie(0),ios::sync_with_stdio(0);
cin >> n >> m;
for(int i = 1;i <= n;i++){
for(int j = 1;j <= m;j++){
cin >> a[i][j];
mn = min(mn,a[i][j]);
}
}
solve();
for(int i = 1;i <= 3;i++){
_rotate();
solve();
}
cout << ans;
}
