#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
int n, m;
vector<int> a, b;
bool check(int mid){
for (int i=0, p=0; i<n; ++i, ++p){
while (p<m&&abs(a[i]-b[p])>mid)++p;
if (p==m)return 0;
}
return 1;
}
int32_t main(){
cin>>n>>m;
a.resize(n);
b.resize(m);
for (int i=0; i<n; ++i)cin>>a[i];
for (int i=0; i<m; ++i)cin>>b[i];
sort(a.begin(), a.end());
sort(b.begin(), b.end());
if (n>m)swap(n, m), swap(a, b);
int low=-1, high=LLONG_MAX/2;
while (low+1<high){
int mid=(low+high)/2;
if (check(mid))high=mid;
else low=mid;
}
cout<<high;
}
