#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
int n, m, mx = 0, mn = INF;
vector< vector<int> > a;
void flip_h() {
for (int j = 1; j <= m; j++) {
for (int i = 1; i <= n / 2; i++) {
swap(a[n - i + 1][j], a[i][j]);
}
}
}
void flip_v() {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m / 2; j++) {
swap(a[i][m - j + 1], a[i][j]);
}
}
}
int check(int k) {
int t = 0;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
if (a[i][j] < mx - k) {
t = max(t, j + 1);
}
}
for (int j = 1; j < t; j++) {
if (a[i][j] > mn + k) {
return 0;
}
}
}
return 1;
}
int solve() {
int lo = 0, hi = mx - mn;
while (lo < hi) {
int mid = (lo + hi) / 2;
if (check(mid)) {
hi = mid;
} else {
lo = mid + 1;
}
}
return lo;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> m;
a.assign(n + 1, vector<int>(m + 2, 0));
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
cin >> a[i][j];
mx = max(mx, a[i][j]);
mn = min(mn, a[i][j]);
}
}
int ans = solve();
flip_h();
ans = min(ans, solve());
flip_v();
ans = min(ans, solve());
flip_h();
ans = min(ans, solve());
cout << ans << '\n';
return 0;
}
