#include<bits/stdc++.h>
#define taskname "C"
using namespace std;
const int INF = 1e9;
template<class T>void minimize(T& a, T b){
if(a > b){
a = b;
}
}
template<class T>void maximize(T& a, T b){
if(a < b){
a = b;
}
}
int n, m;
namespace sub1{
void solve(){
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];
}
}
int ans = INF;
vector<int>current;
auto play = [&] (auto&& self, int p) -> void{
if(p == n){
if(current[0] > 0 && current[n - 1] < m){
int a_max = 0, b_max = 0, a_min = INF, b_min = INF;
for(int i = 0; i < n; i++){
for(int j = 0; j < current[i]; j++){
maximize(a_max, a[i][j]);
minimize(a_min, a[i][j]);
}
for(int j = current[i]; j < m; j++){
maximize(b_max, a[i][j]);
minimize(b_min, a[i][j]);
}
}
minimize(ans, max(a_max - a_min, b_max - b_min));
}
return;
}
for(int i = (current.empty() ? m : current.back()); i > -1; i--){
current.emplace_back(i);
self(self, p + 1);
current.pop_back();
}
};
play(play, 0);
reverse(a.begin(), a.end());
play(play, 0);
cout << ans;
}
}
namespace sub23{
void solve(){
vector<vector<int>>a(n + 1, vector<int>(m + 1)), pref_min(n + 1, vector<int>(m + 1)), suf_max(n + 1, vector<int>(m + 2)), suf_min(n + 1, vector<int>(m + 2));
int x = 1, y = 1;
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++){
cin >> a[i][j];
if(a[i][j] > a[x][y]){
x = i;
y = j;
}
}
}
int ans = INF;
auto eval = [&] (int min_value){
int other_max = 0, other_min = INF;
for(int i = 1, pre = m; i <= n; i++){
int low = 1, high = m, p = 0;
while(low <= high){
int mid = (low + high) >> 1;
if(pref_min[i][mid] >= min_value){
low = (p = mid) + 1;
}
else{
high = mid - 1;
}
}
minimize(pre, p);
if(i == x && pre < y){
return INF;
}
maximize(other_max, suf_max[i][pre + 1]);
minimize(other_min, suf_min[i][pre + 1]);
}
return max(a[x][y] - min_value, max(other_max - other_min, 0));
};
auto work = [&] (){
for(int i = 1; i <= n; i++){
suf_max[i][m + 1] = -(suf_min[i][m + 1] = pref_min[i][0] = INF);
for(int j = 1; j <= m; j++){
pref_min[i][j] = min(pref_min[i][j - 1], a[i][j]);
}
for(int j = m; j > 0; j--){
suf_min[i][j] = min(suf_min[i][j + 1], a[i][j]);
suf_max[i][j] = max(suf_max[i][j + 1], a[i][j]);
}
}
for(int iter = 0, low = 0, high = a[x][y]; iter < 200; iter++){
int mid_1 = low + (high - low) / 3, mid_2 = high - (high - low) / 3, f1 = eval(mid_1), f2 = eval(mid_2);
minimize(ans, min(f1, f2));
if(f1 > f2){
low = mid_1;
}
else{
high = mid_2;
}
}
};
work();
reverse(a.begin() + 1, a.end());
x = n - x + 1;
work();
for(int i = 1; i <= n; i++){
reverse(a[i].begin() + 1, a[i].end());
}
y = n - y + 1;
work();
reverse(a.begin() + 1, a.end());
x = n - x + 1;
work();
cout << ans;
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if(fopen(taskname".inp", "r")){
freopen(taskname".inp", "r", stdin);
}
cin >> n >> m;
if(n <= 10 && m <= 10){
sub1::solve();
}
else{
sub23::solve();
}
}
