#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i=0;i<(n);i++)
typedef long long ll;
//using mint = modint;
using mint = modint998244353;
//using mint = modint1000000007;
using P = pair<int, int>;

const ll INF=1LL<<60, dx[]={0,1,0,-1},dy[]={1,0,-1,0};
template <typename T> inline bool chmin(T& a,const T&b) {if(a>b){a=b; return 1;} return 0;}
template <typename T> inline bool chmax(T& a,const T&b) {if(a<b){a=b; return 1;} return 0;}

int main(){

    int n,m;
    cin >> n >> m;

    vector<vector<ll>> d(n,vector<ll> (m));
    rep(i,n) {
        rep(j,m) cin >> d[i][j];
        sort(d[i].begin(),d[i].end()); 
    }

    auto check=[&](int j,long long k) -> bool {
        ll key=d[0][j]+k;
        for(int i=1;i<n;i++) {
            auto it=lower_bound(d[i].begin(), d[i].end(), key);
            if(it==d[i].end()) return false;
            key=(*it)+k;
        }
        return true;
        
    };

    ll ans=INF;
    rep(i,m){
        long long left=0;//下限
        long long right=1000000001;//上限+1
        long long mid=(left+right)/2;

        while(mid-left>0) {
            mid=(left+right)/2;
            if(check(i,mid)){
                left=mid;	
            } else {
                right=mid;
            }
        }
        chmin(ans,left-1);
    }
    
    cout << ans << endl;

    return 0;
}