#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define mp make_pair
#define pb push_back
#define ld long double
#define ss(x) (int) x.size()
#define FOR(i, j, n) for(int i = j; i <= n; ++i)
#define fi first
#define se second
#define cat(x) cerr << #x << " = " << x << endl;
#define ios cin.tie(0); ios_base::sync_with_stdio(0)
using namespace std;
int n, m;
int a[2002][2002], p[2002][2002];
int ans = 1000000001;
int maks;
int row, col;
void obrot() {
FOR(i, 1, n)
FOR(j, 1, m)
p[j][n - i + 1] = a[i][j];
int rr = col;
int cc = n - row + 1;
swap(n, m);
row = rr;
col = cc;
FOR(i, 1, n)
FOR(j, 1, m)
a[i][j] = p[i][j];
}
int bad[2002];
bool ok(int w) {
int mini = maks - w;
FOR(i, 1, n + 1)
bad[i] = 0;
for(int i = n; 1 <= i; --i) {
for(int j = m; 1 <= j; --j) {
if(a[i][j] < mini) {
bad[i] = j;
break;
}
}
bad[i] = max(bad[i], bad[i + 1]);
}
if(bad[row] >= col)
return 0;
int Max = -1;
int Min = 1e9 + 111;
FOR(i, 1, n)
FOR(j, 1, m) {
if(j <= bad[i]) {
Max = max(Max, a[i][j]);
Min = min(Min, a[i][j]);
}
}
//cout << Max << " " << Min << " " << w << endl;
return Max - Min <= w;
}
void solve() {
int l = 0;
int r = 1000000000;
while(l < r) {
int m = (l + r) / 2;
if(ok(m))
r = m;
else
l = m + 1;
}
ans = min(ans, l);
}
int main() {
scanf("%d %d", &n, &m);
FOR(i, 1, n)
FOR(j, 1, m) {
scanf("%d", &a[i][j]);
if(a[i][j] > maks) {
maks = a[i][j];
row = i;
col = j;
}
}
int k = 4;
while(k--) {
obrot();
/*FOR(i, 1, n) {
FOR(j, 1, m)
cout << a[i][j] << " ";
cout << endl;
}
printf("\n\n");
*/
solve();
}
printf("%d", ans);
return 0;
}
