// #include "aliens.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
double cur = rngesus(0, MASK(60) - 1);
cur /= MASK(60) - 1;
return l + cur * (r - l);
}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
const int N = 2002;
int n, m;
int a[N][N], b[N][N];
int dp[N][N];
int main(void){
ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
clock_t start = clock();
cin >> n >> m;
for(int i= 1; i<=n; ++i)
for(int j = 1; j<=m; ++j) cin >> a[i][j];
int mi = 1e9, ma = 0;
for(int i = 1; i<=n; ++i) for(int j = 1; j<=m; ++j) {
minimize(mi, a[i][j]);
maximize(ma, a[i][j]);
}
// cout << mi << " " << ma << "\n";
int ans = 1e9;
for(int x = 0; x < 4; ++x){
for(int i = 1; i<=n; ++i) for(int j = 1; j<=m; ++j) b[i][j] = a[i][j];
if (GETBIT(x, 0)){
for(int i = 1; i<=n; ++i) reverse(b[i] + 1, b[i] + m + 1);
}
if (GETBIT(x, 1)) {
for(int i = 1; i<=n/2; ++i) {
for(int j= 1; j<=m; ++j) swap(b[i][j], b[n - i + 1][j]);
}
}
vector<int> dp(m+1);
for(int i= 1; i<=n; ++i){
vector<int> cu(m+1);
int cur = 0;
for(int j = 1; j<=m; ++j){
maximize(cur, b[i][j] - mi);
maximize(cu[j], cur);
}
cur = 0;
for(int j = m; j>=1; --j){
maximize(cur, ma - b[i][j]);
maximize(cu[j-1], cur);
}
for(int j = 0; j<=m; ++j) maximize(dp[j], cu[j]);
for(int j = m-1; j>=0; --j) minimize(dp[j], dp[j+1]);
}
minimize(ans, dp[0]);
}
cout << ans << "\n";
cerr << "Time elapsed: " << clock() - start << " ms\n";
return 0;
}
