#include <bits/stdc++.h>
// Author: Kazuki_Will_Win_VOI_8703
#define fi first
#define se second
#define pii pair<int, int>
#define int long long
#define all(a) a.begin(), a.end()
using namespace std;
const int mn = 2e3 + 5, inf = 1e9;
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
int h, w, a[mn][mn], b[mn][mn], min_val = inf;
void Megumi(){
for(int i = 1; i <= h; i++){
for(int j = 1; j <= w; j++){
b[j][h - i + 1] = a[i][j];
}
}
swap(w, h);
for(int i = 1; i <= h; i++){
for(int j = 1; j <= w; j++){
a[i][j] = b[i][j];
}
}
}
bool check(int val){
int mn = inf, mx = 0;
for(int i = 1; i <= h; i++){
bool ok = true;
for(int j = 1; j <= w; j++){
if(a[i][j] - min_val > val && ok){
ok = false;
}
if(!ok){
mn = min(mn, a[i][j]);
mx = max(mx, a[i][j]);
}
}
}
return (mx - mn <= val);
}
void solve(){
cin >> h >> w;
for(int i = 1; i <= h; i++){
for(int j = 1; j <= w; j++){
cin >> a[i][j];
if(min_val > a[i][j]){
min_val = a[i][j];
}
}
}
int ans = inf;
for(int i = 1; i <= 4; i++){
int l = 1, r = 1e9, cur = inf;
while(l <= r){
int mid = (l + r) >> 1;
if(check(mid)){
cur = mid;
r = mid - 1;
}
else l = mid + 1;
}
ans = min(ans, cur);
if(i < 4) Megumi();
}
cout << ans << '\n';
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int t = 1;
// cin >> t;
while(t--) solve();
}
