#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ii pair<int, int>
#define fi first
#define se second
#define pb push_back
#define FOR(a, b, c) for(int a = b; a <= c; ++a)
const int N = 2009;
const int oo = 1e9 + 10;
const int mod = 1e9 + 7;
int n, m, ans = oo, imin = oo;
int a[N][N], tmp[N][N], Rmin[N][N], Rmax[N][N], pos[N];
void _rorate() {
for(int i = 1; i <= n; ++i) for(int j = 1; j <= m; ++j)
tmp[j][n - i + 1] = a[i][j];
swap(n, m);
for(int i = 1; i <= n; ++i) for(int j = 1; j <= m; ++j)
a[i][j] = tmp[i][j];
}
bool check(int val) {
// we save
for(int i = 1; i <= n; ++i) {
pos[i] = m + 1;
for(int j = 1; j <= m; ++j) if(a[i][j] - imin > val) {
pos[i] = j; break;
}
}
for (int i = 1; i <= n; ++i) {
Rmin[i][m + 1] = oo, Rmax[i][m + 1] = 0;
for (int j = m; j >= 1; --j) {
Rmin[i][j] = min(Rmin[i][j + 1], a[i][j]);
Rmax[i][j] = max(Rmax[i][j + 1], a[i][j]);
}
}
int cur = oo, curmin = oo, curmax = 0;
for(int i = 1; i <= n; ++i) {
cur = min(cur, pos[i] - 1);
curmin = min(curmin, Rmin[i][cur + 1]);
curmax = max(curmax, Rmax[i][cur + 1]);
}
return ( curmax - curmin <= val );
}
void solve() {
int l = 0, r = oo;
while(r > l) {
int mid = (l + r) /2;
if(check(mid) == true) r = mid;
else l = mid + 1;
}
if(check(l)) ans = min(ans, l);
}
signed main()
{
//freopen("test.txt", "r", stdin);
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin >> n >> m;
FOR(i, 1, n) FOR(j, 1, m) cin >> a[i][j], imin = min(imin, a[i][j]);
solve();
_rorate(); solve();
_rorate(); solve();
_rorate(); solve();
cout << ans;
}
