#include<bits/stdc++.h>
#define ll long long
#define lll __int128_t
#define f first
#define s second
using namespace std;
const int mod = 1e9 + 7;
const int N = 1e5 + 5;
const ll INF = 1e18 + 7;
int n, m;
vector<int> a(N), b(N);
bool check(int val){
int p = 1;
for(int i = 1; i <= n; i++){
int l = a[i] - val, r = a[i] + val;
while(p <= m && (b[p] < l || b[p] > r)) p++;
p++;
}
return p <= m + 1;
}
signed main(){
// freopen(".inp", "r", stdin);
//
// freopen(".out", "w", stdout);
// ios_base::sync_with_stdio(0);
//
// cin.tie(0); cout.tie(0);
cin>>n>>m;
for(int i = 1; i <= n; i++) cin>>a[i];
for(int i = 1; i <= m; i++) cin>>b[i];
if(n > m){
swap(n, m);
swap(a, b);
}
sort(a.begin() + 1, a.begin() + n + 1);
sort(b.begin() + 1, b.begin() + m + 1);
int l = 0, r = 1e9, mid;
while(l <= r){
int mid = (l + r) >> 1;
// cout<<l<<" "<<r<<" "<<mid<<'\n';
if(check(mid)) r = mid - 1;
else l = mid + 1;
}
cout<<l;
}
