#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2000;
const int INF = 1e9;
int n, m;
int a[MAXN+1][MAXN+1];
int tmp[MAXN+1][MAXN+1];
int pre[MAXN+1][MAXN+1];
int suf_mmax[MAXN+2][MAXN+2];
int suf_mmin[MAXN+2][MAXN+2];
int R[MAXN+1];
int mmin;
int ans;
bool solve(int n, int m, int val) {
for (int i = 1; i <= n; i++) {
R[i] = upper_bound(pre[i]+1, pre[i]+1+m, mmin+val) - pre[i] - 1;
if (i > 1) R[i] = min(R[i], R[i-1]);
}
if (!R[1]) return false;
int _mmax = 0, _mmin = INF;
for (int i = 1; i <= n; i++) {
_mmax = max(_mmax, suf_mmax[i][R[i]+1]);
_mmin = min(_mmin, suf_mmin[i][R[i]+1]);
}
if (_mmax - _mmin > val) return false;
return true;
}
int cal(int n, int m) {
int l = 0, r = 1e9, mid;
while (l < r) {
mid = l + r >> 1;
if (!solve(n, m, mid))
l = mid + 1;
else
r = mid;
}
return l;
}
void rotate(int n, int m, bool flag) {
int N = max(n, m);
for (int i = 1; i <= N; i++)
for (int j = 1; j <= N; j++)
tmp[i][j] = a[j][i];
if (!flag) {
for (int i = 1; i <= m; i++)
for (int j = 1; j <= n/2; j++)
swap(tmp[i][j], tmp[i][n-j+1]);
}
for (int i = 1; i <= N; i++)
for (int j = 1; j <= N; j++)
a[i][j] = tmp[i][j];
for (int i = 1; i <= m; i++)
for (int j = 1; j <= n; j++)
pre[i][j] = max({a[i][j], pre[i-1][j], pre[i][j-1]});
for (int i = 1; i <= N+1; i++) {
for (int j = 1; j <= N+1; j++) {
suf_mmin[i][j] = INF;
suf_mmax[i][j] = 0;
}
}
for (int i = m; i >= 1; i--) {
for (int j = n; j >= 1; j--) {
suf_mmin[i][j] = min({a[i][j], suf_mmin[i+1][j], suf_mmin[i][j+1]});
suf_mmax[i][j] = max({a[i][j], suf_mmax[i+1][j], suf_mmax[i][j+1]});
}
}
return;
for (int i = 1; i <= N; i++)
for (int j = 1; j <= N; j++)
cout << a[i][j] << " \n"[j==N];
cout << "\n";
}
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0);
cin >> n >> m;
mmin = INF;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
cin >> a[i][j];
mmin = min(mmin, a[i][j]);
}
}
ans = INF;
rotate(n, m, true);
ans = min(ans, cal(m, n));
rotate(m, n, false);
ans = min(ans, cal(n, m));
rotate(n, m, false);
ans = min(ans, cal(m, n));
rotate(m, n, false);
ans = min(ans, cal(n, m));
cout << ans << "\n";
}
