#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define sz(x) (int)x.size()
#define ALL(v) v.begin(),v.end()
#define MASK(k) (1LL << (k))
#define BIT(x, i) (((x) >> (i)) & 1)
#define oo (ll)1e18
#define INF (ll)1e9
#define MOD (ll)(1e9 + 7)
using namespace std;
template<class T1, class T2>
bool maximize(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}
template<class T1, class T2>
bool minimize(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}
template<class T1, class T2>
void add(T1 &a, T2 b){a += b; if(a >= MOD) a -= MOD;}
template<class T1, class T2>
void sub(T1 &a, T2 b){a -= b; if(a < 0) a += MOD;}
template<class T>
void cps(T &v){sort(ALL(v)); v.resize(unique(ALL(v)) - v.begin());}
const int MAX = 2e3 + 10;
int N, M;
int a[MAX][MAX], b[MAX][MAX], c[MAX][MAX], d[MAX][MAX], ma, mi = INF;
bool OK(int k, int a[MAX][MAX]){
vector<vector<int>> val(N + 3, vector<int>(M + 3, 0));
for(int i = 1; i <= N; i++){
for(int j = 1; j <= M; j++){
if(a[i][j] - mi <= k) val[i][j] += 1;
if(ma - a[i][j] <= k) val[i][j] += 2;
if(val[i][j] == 0) return false;
}
}
int cur = M, t = 0;
for(int i = 1; i <= N; i++){
for(int j = 1; j <= cur; j++){
if(val[i][j] == 3 || val[i][j] == t) continue;
if(t == 0) t = val[i][j];
else{
cur = j - 1;
break;
}
}
for(int j = cur + 1; j <= M; j++){
if(val[i][j] != 3 && val[i][j] == t) return false;
}
}
return true;
}
void solve(){
cin >> N >> M;
for(int i = 1; i <= N; i++){
for(int j = 1; j <= M; j++){
cin >> a[i][j];
maximize(ma, a[i][j]);
minimize(mi, a[i][j]);
}
}
for(int i = 1; i <= N; i++){
for(int j = 1; j <= M; j++){
b[i][j] = a[i][M + 1 - j];
c[i][j] = a[N + 1 - i][j];
d[i][j] = a[N + 1 - i][M + 1 - j];
}
}
int l = 0, r = ma - mi;
while(l < r){
int m = (l + r) >> 1;
if(OK(m, a) || OK(m, b) || OK(m, c) || OK(m, d)){
r = m;
}
else{
l = m + 1;
}
}
cout << r << '\n';
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen("order.inp","r",stdin);
// freopen("order.out","w",stdout);
solve();
return 0;
}
