/***Farhan132***/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef double dd;
typedef vector<ll> vll;
typedef pair<ll , ll> ii;
typedef vector< ii > vi;
typedef pair < pair < ll , ll > , pair < ll , ll > > cm;
#define ff first
#define ss second
#define pb push_back
#define in insert
#define f0(b) for(int i=0;i<(b);i++)
#define f00(b) for(int j=0;j<(b);j++)
#define f1(b) for(int i=1;i<=(b);i++)
#define f11(b) for(int j=1;j<=(b);j++)
#define f2(a,b) for(int i=(a);i<=(b);i++)
#define f22(a,b) for(int j=(a);j<=(b);j++)
#define sf(a) scanf("%lld",&a)
#define sff(a,b) scanf("%lld %lld", &a , &b)
#define pf(a) printf("%lld\n",a)
#define pff(a,b) printf("%lld %lld\n", a , b)
#define PI 3.14159265359
#define bug printf("**!\n")
#define mem(a , b) memset(a, b ,sizeof(a))
#define front_zero(n) __builtin_clzll(n)
#define back_zero(n) __builtin_ctzll(n)
#define total_one(n) __builtin_popcountll(n)
#define clean fflush(stdout)
const ll mod = (ll)1e9 + 7;
const ll maxn = (ll)2e5 + 5;
const int nnn = 1048590;
const int inf = numeric_limits<int>::max()-1;
//const ll INF = numeric_limits<ll>::max()-1;
//const ll INF = 1e18;
ll dx[]={0,1,0,-1};
ll dy[]={1,0,-1,0};
ll dxx[]={0,1,0,-1,1,1,-1,-1};
ll dyy[]={1,0,-1,0,1,-1,1,-1};
ll a[2005][2005];
ll b[2005][2005];
ll n , m;
void rotate(){
f1(n){
f11(m) b[i][j] = a[i][j];
}
ll N = m , M = n;
for(ll i = N; i >= 1; i--){
for(ll j = 1; j <= M; j++) a[i][j] = b[j][N - i + 1];
}
swap(n, m);
return;
}
ll mn = 1e12, mx = 0;
bool check(ll x){
ll big = m;
for(ll i = 1; i <= n; i++){
for(ll j = 1; j <= m; j++){
ll ok1 = 0, ok2 = 0;
if(a[i][j] > x) ok1 = 1;
if(a[i][j] < mx-x) ok2 = 1;
if(ok1 && ok2) return 0;
if(j > big){
if(ok2) return 0;
}else{
if(ok1){
big = j - 1;
}
}
}
}
return 1;
}
void solve(){
cin >> n >> m;
for(ll i = 1; i <= n; i++){
for(ll j = 1; j <= m; j++) cin >> a[i][j] , mn = min(mn, a[i][j]);
}
for(ll i = 1; i <= n; i++){
for(ll j = 1; j <= m; j++) a[i][j] -= mn , mx = max(mx, a[i][j]);
}
ll ans = mx;
f1(4){
ll lo = 0, hg = mx, res = 0;
while(lo <= hg){
ll mid = (lo + hg)/2;
if(check(mid)) res = mid , hg = mid-1;
else lo = mid+1;
}
ans = min(ans, res);
rotate();
}
cout << ans;
return;
}
int main() {
#ifdef LOCAL
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#else
// freopen("cbarn2.in", "r", stdin);
// freopen("cbarn2.out", "w", stdout);
ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
#endif
//cout << fixed << setprecision(10);
// work(maxn);
// mem(b,0);
ll T;
T=1;
//cin >> T;
//scanf("%lld",&T);
// ll CT = 0;
//work();
while(T--){
//cout << "Case " << ++CT <<": " ;
//printf("Case %lld: ",++CT);
solve();
}
return 0;
}
