#include<bits/stdc++.h>
#define fi first
#define se second
#define pitem item*
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vl;
const int N=1e6+10;
const int SS=1<<19;
const int INFi=2e9;
const ll INFl=1e13;
const ll mod=998244353;
const ll mod2=1e9+7;
const ll mod3=1000696969;
const ll p=70032301;
const ull p2=913;
const int L=20;
int t1[N],t2[N];
int n,m;
bool check(int x){
int wsk=m;
for(int i=n;i>=1;i--){
while(wsk>0 and abs(t1[i]-t2[wsk])>x) wsk--;
if(wsk==0) return 0;
wsk--;
}
return 1;
}
int bs(int pocz,int kon){
int res=0;
while(pocz<=kon){
int sr=(pocz+kon)>>1;
if(check(sr)) res=sr,kon=sr-1;
else pocz=sr+1;
}
return res;
}
void solve(){
cin>>n>>m;
for(int i=1;i<=n;i++) cin>>t1[i];
for(int i=1;i<=m;i++) cin>>t2[i];
sort(t1+1,t1+1+n),sort(t2+1,t2+1+m);
if(m<n){
for(int i=1;i<=max(n,m);i++) swap(t1[i],t2[i]);
swap(n,m);
}
cout<<bs(0,1e9)<<"\n";
}
int main(){
ios_base::sync_with_stdio(0),cin.tie(0);
solve();
}
