#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
int inf = 2e9;
void solve(){
int n, m;
cin >> n >> m;
vector<vector<int>> a(n, vector<int> (m));
array<int,3> mx = {0, 0, 0}, mn = {inf, 0, 0};
for(int i = 0; i < n; i ++ )
for(int j = 0; j < m; j ++ ){
cin >> a[i][j];
if(mx[0] <= a[i][j]) mx = {a[i][j], i, j};
if(mn[0] >= a[i][j]) mn = {a[i][j], i, j};
}
int l = 0, r = mx[0] - mn[0], ans = r;
//vector<int> dx = {-1,1,0,0}, dy = {0,0,-1,1};
//auto ok = [&](int i, int j) -> bool {
//return (i >= 0 && i < n && j >= 0 && j < m);
//};
auto rota = [&]() {
vector<vector<int>> na(m, vector<int>(n));
for(int nj = 0, j = m-1; j >= 0; nj ++, j -- ){
for(int i = 0; i < n; i ++ )
na[nj][i] = a[i][j];
}
a = na;
swap(n, m);
};
auto ch = [&]( int mid ) -> bool {
for(int k = 0; k < 4; k ++ ){
int la = m-1, cmx = 0;
for(int i = 0; i < n; i ++ ) {
for(int j = 0; j < m; j ++ ){
if(mx[0] - a[i][j] > mid) la = min(la, j-1);
if(j > la){
cmx = max(cmx, a[i][j]);
}
}
}
if(cmx - mn[0] <= mid) return 1;
rota();
}
return 0;
};
while( l <= r ) {
int m = (l + r) >> 1;
if(ch(m)){
ans = m;
r = m - 1;
}else l = m + 1;
};
cout << ans << '\n';
};
signed main(){
ios_base::sync_with_stdio();
cin.tie(nullptr); cout.tie(nullptr);
int tt = 1;
//cin >> tt;
while(tt -- ){
solve();
};
};
