#include<bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define pb push_back
#define sz(x) (int)(x.size())
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
#define vi vector<int>
#define vp vector<pii>
#define vvi vector<vi>
#define ykh mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count())
#define __lg(x) 63-__builtin_clzll(x)
#define pow2(x) (1LL<<x)
void __print(int x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef local
void setio(){freopen("/Users/iantsai/Library/Mobile Documents/com~apple~CloudDocs/cpp/Empty.md","r",stdin);}
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
void setio(){}
#define debug(x...)
#endif
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
struct line{
int a,b;
int operator()(const int x)const{
return a*x+b;
}
};
bool check(line l1,line l2,line l3){
return (l3.b-l2.b)*(l1.a-l2.a)<=(l2.b-l1.b)*(l2.a-l3.a);
}
const int mxn=2005;
int a[mxn][mxn];
int n,m;
int ans=0,mn,mx,mm;
bool ok(){
vector<int>last(n+1);
last[0]=m;
for(int i=1;i<=n;i++){
for(int j=1;j<=last[i-1];j++){
if(a[i][j]<=mn+mm){
last[i]++;
}
else{
break;
}
}
for(int j=last[i]+1;j<=m;j++){
if(a[i][j]<mx-mm){
return 0;
}
}
}
return 1;
}
signed main(){
setio();
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n>>m;
mn=1e18;
mx=-1e18;
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
cin>>a[i][j];
chmax(mx,a[i][j]);
chmin(mn,a[i][j]);
}
}
int l=0,r=1e9;
while(l<r){
mm=l+r>>1;
bool tf=0;
tf|=ok();
for(int i=1;i<=n;i++){
reverse(a[i]+1,a[i]+m+1);
}
tf|=ok();
reverse(a+1,a+n+1);
tf|=ok();
for(int i=1;i<=n;i++){
reverse(a[i]+1,a[i]+m+1);
}
tf|=ok();
reverse(a+1,a+n+1);
if(tf){
r=mm;
}
else{
l=mm+1;
}
}
cout<<l<<'\n';
}
/*
input:
*/
