#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;
using ll = long long;
using ld = long double;
template<class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<class T>
using pq = priority_queue<T, vector<T>, greater<T>>;
const ll INF = 1e15;
ll MOD = 1e5 + 1;
ll MAXn = 2e6;
ll lg = 22;
const ld ap = 1e-6;
const double pi = acos(-1);
using rc = complex<double>;
template<class T>
istream &operator>>(istream &in, vector<T> &x) {
for (auto &i : x) {
in >> i;
}
return in;
}
template<class T>
ostream &operator<<(ostream &out, vector<T> &x) {
for (auto &i : x) {
out << i << ' ';
}
return out;
}
struct el {
ll x, t, i, j;
};
bool cmp(el a, el b) {
return a.x > b.x;
}
bool check(ll n, ll m, vector<vector<ll>> is) {
ll f = max(0ll, is[0][0]);
ll pr = m;
for (ll i = 0; i < n; i++) {
ll lst = -1;
if (is[i][0] == 0) lst = 0;
if (is[i][0] == -1) {
is[i][0] = f;
}
ll cn = is[i][0] == 0;
for (ll j = 1; j < m; j++) {
if (is[i][j] == 0) lst = j;
if (is[i][j] != -1) {
is[i][j] ^= f;
} else {
is[i][j] = is[i][j - 1];
}
if (is[i][j - 1] == 1 && is[i][j] == 0) return 0;
if (is[i][j] == 0) cn++;
}
if (lst + 1 > pr) return 0;
pr = min(pr, cn);
}
return 1;
}
void rotate(ll &n, ll &m, vector<vector<ll>> &is) {
vector<vector<ll>> res(m, vector<ll>(n));
for (ll i = 0; i < m; i++) {
for (ll j = 0; j < n; j++) {
res[i][j] = is[n - j - 1][i];
}
}
is = res;
swap(n, m);
}
void viperr() {
ll n, m;
cin >> n >> m;
vector<vector<ll>> a(n, vector<ll>(m));
for (auto &i : a) cin >> i;
deque<pair<ll, pair<ll, ll>>> b;
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < m; j++) {
b.emplace_back(a[i][j], pair<ll, ll>{i, j});
}
}
std::sort(b.begin(), b.end());
vector<el> c;
for (ll i = 1; i < b.size() - 1; i++) {
c.emplace_back(max(b.back().first - b[i].first, b[i].first - b.front().first),
b.back().first - b[i].first < b[i].first - b.front().first, b[i].second.first,
b[i].second.second);
}
std::sort(c.begin(), c.end(), cmp);
ll l = 0, r = c.size();
while (r - l > 1) {
ll x = (r + l) / 2;
vector<vector<ll>> is(n, vector<ll>(m, -1));
for (ll i = 0; i <= x; i++) {
is[c[i].i][c[i].j] = c[i].t;
}
bool res = check(n, m, is);
rotate(n, m, is);
res |= check(n, m, is);
rotate(n, m, is);
res |= check(n, m, is);
rotate(n, m, is);
res |= check(n, m, is);
rotate(n, m, is);
if (res) l = x;
else r = x;
}
c.emplace_back(0, 0, 0, 0);
cout << max(c[l + 1].x, b.back().first - b.front().first - c[l].x);
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t11 = 1;
// cin >> t11;
while (t11--) {
viperr();
cout << '\n';
}
return 0;
}
