#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 2005;
const int movex[] = {1, -1, 0, 0};
const int movey[] = {0, 0, 1, -1};
int n, m, a[maxn][maxn];
int mr, mc;
bool vis[maxn][maxn];
bool region[maxn][maxn];
bool check(int mid) {
int mn = 1e9, mx = -1;
int l = n;
for(int j = 1; j <= m; ++j) {
for(int i = 1; i <= l; ++i) {
if(a[i][j] - a[mr][mc] > mid) {
l = i - 1;
break;
}
}
for(int i = l + 1; i <= n; ++i) {
mn = min(mn, a[i][j]);
mx = max(mx, a[i][j]);
}
}
if(mx == -1 || mx - mn <= mid) return 1;
return 0;
}
void solve() {
cin >> n >> m;
for(int i = 1; i <= n; ++i) {
for(int j = 1; j <= m; ++j) {
cin >> a[i][j];
}
}
int res = 1e9;
for(int ix = 0; ix < 2; ++ix) {
for(int iy = 0; iy < 2; ++iy) {
for(int i = 1; i <= n; ++i) {
for(int j = 1; j <= m; ++j) {
if(!mr || a[i][j] < a[mr][mc]) {
mr = i, mc = j;
}
}
}
int l = 0, r = res;
while(l <= r) {
int mid = (l + r) >> 1;
if(check(mid)) {
res = mid;
r = mid - 1;
} else {
l = mid + 1;
}
}
for(int i = 1; i <= n; ++i) {
reverse(a[i] + 1, a[i] + m + 1);
}
}
for(int j = 1; j <= m; ++j) {
for(int i = 1; i <= n / 2; ++i) {
swap(a[i][j], a[n - i + 1][j]);
}
}
}
cout << res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
