#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
#define int long long
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define ppb pop_back
#define eb emplace_back
#define g0(a) get<0>(a)
#define g1(a) get<1>(a)
#define g2(a) get<2>(a)
#define g3(a) get<3>(a)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using db = double;
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using iii = tuple<int, int, int>;
using iiii = tuple<int, int, int, int>;
template<class key, class value = null_type, class cmp = less<key> >
using ordered_set = tree<key, value, cmp, rb_tree_tag, tree_order_statistics_node_update>;
int tans = LLONG_MAX, H, W, _A[2005][2005], A[2005][2005], lim[2005];
int solve() {
int lo = 0, hi = 1e9, ans = -1;
iii mx = mt(0, 0, 0);
for (int i = 1; i <= H; i++)
for (int j = 1; j <= W; j++)
mx = max(mx, mt(A[i][j], i, j));
while (lo <= hi) {
int mid = (lo + hi) / 2, mi2 = 1e9, mx2 = 0;
for (int i = 1; i <= H; i++) {
lim[i] = W + 1;
for (int j = 1; j <= W; j++)
if (g0(mx) - A[i][j] > mid) {
lim[i] = j;
break;
}
lim[i]--;
}
for (int j = H - 1; j >= 1; j--) lim[j] = min(lim[j], lim[j + 1]);
bool inv = lim[g1(mx)] < g2(mx);
for (int i = 1; i <= H; i++)
for (int j = lim[i] + 1; j <= W; j++)
mi2 = min(mi2, A[i][j]), mx2 = max(mx2, A[i][j]);
inv |= mx2 - mi2 > mid;
if (inv) lo = mid + 1;
else ans = mid, hi = mid - 1;
}
assert(ans != -1);
return ans;
}
void reflect_hor() {
for (int i = 1; i <= H; i++)
for (int j = 1; j <= W; j++)
_A[i][j] = A[i][j];
for (int i = 1; i <= H; i++)
for (int j = 1; j <= W; j++)
A[i][j] = _A[i][W - j + 1];
}
void rotate_90() {
for (int i = 1; i <= H; i++)
for (int j = 1; j <= W; j++)
_A[i][j] = A[i][j];
for (int i = 1; i <= W; i++)
for (int j = 1; j <= H; j++)
A[i][j] = _A[H - j + 1][i];
swap(H, W);
}
main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> H >> W;
for (int i = 1; i <= H; i++)
for (int j = 1; j <= W; j++)
cin >> A[i][j];
for (int k = 0; k < 4; k++) {
tans = min(tans, solve());
reflect_hor();
tans = min(tans, solve());
reflect_hor();
rotate_90();
}
cout << tans << '\n';
}
