#include <bits/stdc++.h>
#include <bits/extc++.h>
#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define ef(a) emplace_front(a)
#define pob pop_back()
#define pof pop_front()
#define mp(a, b) make_pair(a, b)
#define F first
#define S second
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define iceil(a, b) (((a) + (b) - 1) / (b))
#define tomax(a, b) ((a) = max((a), (b)))
#define tomin(a, b) ((a) = min((a), (b)))
#define topos(a) ((a) = (((a) % MOD + MOD) % MOD))
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
if(pvaspace) b << " "; pvaspace=true;\
b << pva;\
}\
b << "\n";}
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using tiii = tuple<int, int, int>;
const ll MOD = 1000000007;
const ll MAX = 2147483647;
template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
return o << '(' << p.F << ',' << p.S << ')';
}
int mx = 0, mn = MAX;
bool check(int n, int m, vector<vector<int>>& a, int d){
// cerr << "check " << d << "\n";
// for(int i = 0; i < n; i++){
// for(int j = 0; j < m; j++){
// if(mx - a[i][j] > d && a[i][j] - mn > d) cerr << "-1 ";
// else if(mx - a[i][j] <= d && a[i][j] - mn <= d) cerr << "0 ";
// else if(mx - a[i][j] <= d) cerr << "1 ";
// else cerr << "2 ";
// }
// cerr << "\n";
// }
int pos = -1;
for(int i = 0; i < n; i++){
bool right = false;
for(int j = 0; j < m; j++){
if(mx - a[i][j] > d && a[i][j] - mn > d) return false;
if(mx - a[i][j] <= d && a[i][j] - mn <= d) continue;
if(mx - a[i][j] <= d){
if(right) return false;
pos = max(pos, j);
}
else{
if(j <= pos) return false;
right = true;
}
}
}
// cerr << "ok\n";
return true;
}
int calc(int n, int m, vector<vector<int>>& a){
int l = 0, r = 1000000000;
while(l < r){
// cerr << l << " " << r << "\n";
int mid = (l + r) / 2;
if(check(n, m, a, mid)) r = mid;
else l = mid + 1;
}
return l;
}
int main(){
StarBurstStream
int n, m;
cin >> n >> m;
vector<vector<int>> a(n, vector<int>(m));
for(int i = 0; i < n; i++){
for(int j = 0; j < m; j++){
cin >> a[i][j];
mx = max(mx, a[i][j]);
mn = min(mn, a[i][j]);
}
}
int ans = calc(n, m, a);
for(int i = 0; i < n; i++) reverse(iter(a[i]));
// cerr << "OwO\n";
// for(int i = 0; i < n; i++) printv(a[i], cerr);
ans = min(ans, calc(n, m, a));
reverse(iter(a));
// cerr << "OwO\n";
// for(int i = 0; i < n; i++) printv(a[i], cerr);
ans = min(ans, calc(n, m, a));
for(int i = 0; i < n; i++) reverse(iter(a[i]));
// cerr << "OwO\n";
// for(int i = 0; i < n; i++) printv(a[i], cerr);
ans = min(ans, calc(n, m, a));
cout << ans << "\n";
return 0;
}
