#include <bits/stdc++.h>
// #pragma GCC optimize ("Ofast,unroll-loops")
// #pragma GCC target ("avx2")
using namespace std;
typedef long long ll;
typedef pair<int, int> pp;
#define per(i,r,l) for(int i = (r); i >= (l); i--)
#define rep(i,l,r) for(int i = (l); i < (r); i++)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define pb push_back
#define ss second
#define ff first
void err(istringstream *iss){}template<typename T,typename ...Args> void err(istringstream *iss,const T &_val, const Args&...args){string _name;*iss>>_name;if(_name.back()==',')_name.pop_back();cerr<<_name<<" = "<<_val<<", ",err(iss,args...);}
void IOS(){
cin.tie(0) -> sync_with_stdio(0);
#ifndef ONLINE_JUDGE
#define er(args ...) cerr << __LINE__ << ": ", err(new istringstream(string(#args)), args), cerr << endl
#else
#define er(args ...) 0
#endif
}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll mod = 1e9 + 7, maxn = 2e3 + 5, lg = 22, inf = ll(1e9) + 5;
ll pw(ll a,ll b,ll md=mod){if(!b)return 1;ll k=pw(a,b>>1ll,md);return k*k%md*(b&1ll?a:1)%md;}
int n, m;
int a[maxn][maxn], b[maxn][maxn];
pair<int, pp> mx;
ll slv(){
// er(mx.ff, mx.ss.ff, mx.ss.ss);
auto get = [&](int x){
x = mx.ff - x - 1;
int ptr = n;
int mxx = 0, mnn = inf;
rep(j,0,m){
rep(i,0,ptr) if(a[i][j] <= x){
ptr = i;
break;
}
// er(j, ptr);
if(j == mx.ss.ss){
if(ptr <= mx.ss.ff) return int(inf);
}
rep(i,ptr,n){
mxx = max(mxx, a[i][j]);
mnn = min(mnn, a[i][j]);
}
}
return mxx - mnn;
};
int lx = -1, rx = mx.ff;
while(lx + 1 < rx){
int mid = (lx + rx)>>1;
// er(mid, get(mid));
if(mid < get(mid)) lx = mid;
else rx = mid;
}
// er(lx);
return min(lx+1, get(lx));
}
int main(){ IOS();
cin >> n >> m;
rep(i,0,n){
rep(j,0,m) {
cin >> a[i][j];
mx = max(mx, {a[i][j], {i, j}});
}
}
ll ans = slv();
// rep(i,0,n){
// rep(j,0,m){
// b[i][j] = a[n-1-i][m-1-j];
// }
// }
// rep(i,0,n){
// rep(j,0,m){
// a[i][j] = b[i][j];
// }
// }
// mx.ss.ff = n-1-mx.ss.ff, mx.ss.ss = m-1-mx.ss.ss;
// ans = min(ans, slv());
rep(i,0,n){
rep(j,0,m){
b[i][j] = a[i][m-1-j];
}
}
rep(i,0,n){
rep(j,0,m){
a[i][j] = b[i][j];
}
}
mx.ss.ss = m-1-mx.ss.ss;
ans = min(ans, slv());
rep(i,0,n){
rep(j,0,m){
b[i][j] = a[n-1-i][j];
}
}
rep(i,0,n){
rep(j,0,m){
a[i][j] = b[i][j];
}
}
mx.ss.ff = n-1-mx.ss.ff;
ans = min(ans, slv());
rep(i,0,n){
rep(j,0,m){
b[i][j] = a[i][m-1-j];
}
}
rep(i,0,n){
rep(j,0,m){
a[i][j] = b[i][j];
}
}
mx.ss.ss = m-1-mx.ss.ss;
ans = min(ans, slv());
cout << ans << '\n';
}
