#include <algorithm>
#include <iostream>
#include <iomanip>
#include <numeric>
#include <cassert>
#include <vector>
#include <random>
#include <cmath>
#include <queue>
#include <set>
#include <map>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<30;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-8;
const ll mod=998244353;
const int dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};
vi vin(int n,int d=0){
vi a(n);
for(auto &i:a){
cin>>i;
i-=d;
}
return a;
}
int n,m;
vi a,b;
bool f(int d){
int I=0;
for(int i=0;i<n;i++){
while(I<m&&a[i]-b[I]>d) I++;
if(I==m||abs(a[i]-b[I])>d) return 0;
I++;
}
return 1;
}
int main(){
cin>>n>>m;
a=vin(n);b=vin(m);
if(n>m){swap(n,m);swap(a,b);}
sort(a.begin(),a.end());
sort(b.begin(),b.end());
int l=-1,r=inf;
while(r-l>1){
int md=(l+r)/2;
if(f(md)) r=md;
else l=md;
}
cout<<r<<endl;
}
