#include <bits/stdc++.h>
using namespace std;
#define pii pair<int, short>
const int N = 2e3+110;
const int INF = 1e9;
int a[N][N], cnt[N], h, w;
vector<int> v;
void fs(int &number) {
register int c;
number = 0;
c = getchar();
for (; (c>47 && c<58); c=getchar()) number = number *10 + c - 48;
}
int solve() {
memset(cnt, 0, sizeof(cnt));
int res=INF;
multiset<int> js;
int lis=INF, uis=-1;
for (int i=1; i<=h; ++i) {
for (int j=1; j<=w; ++j) js.insert(a[i][j]);
}
priority_queue<pii, vector<pii>, greater<pii>> pq;
pq.push({a[1][w], w});
for (int k=0; k<(int)v.size(); ++k) {
while (!pq.empty()) {
if (pq.top().first <= v[k]) {
pii x=pq.top(); pq.pop();
js.erase(js.find(x.first));
lis=min(lis, x.first), uis=max(uis, x.first);
++cnt[x.second];
if (cnt[x.second] == h) continue;
if (x.second == w || cnt[x.second+1] >= cnt[x.second]+1) {
pq.push({a[cnt[x.second]+1][x.second], x.second});
}
if (x.second == 1) continue;
if (cnt[x.second] == cnt[x.second-1]+1) {
pq.push({a[cnt[x.second]][x.second-1], x.second-1});
}
} else break;
}
int lf;
if (js.empty()) lf=INF;
else lf=(*js.rbegin())-(*js.begin());
res=min(res, max(lf, uis-lis));
}
return res;
}
void hor() {
for (int i=1; i<h/2+1; ++i) {
for (int j=1; j<=w; ++j) swap(a[i][j], a[h-i+1][j]);
}
}
void ver() {
for (int i=1; i<=h; ++i) {
for (int j=1; j<w/2+1; ++j) swap(a[i][j], a[i][w-j+1]);
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
fs(h), fs(w);
for (int i=1; i<=h; ++i) {
for (int j=1; j<=w; ++j) {
fs(a[i][j]);
v.push_back(a[i][j]);
}
} sort(v.begin(), v.end());
v.erase(unique(v.begin(), v.end()), v.end());
int ans=solve();
hor(); ans=min(ans, solve()); hor();
ver();
ans=min(ans, solve());
hor(); ans=min(ans, solve()); hor();
printf("%d\n", ans);
}
