#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define vi vector<int>
#define fo(i,a,b) for(int i=(a);i<=(b);++i)
#define fd(i,a,b) for(int i=(a);i>=(b);--i)
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define maxi(a,b) a=max(a,b)
#define mini(a,b) a=min(a,b)
#define ii pair<int,int>
const int N = 1e6+5, mod = 1e9+7;
int n, m, a[N], b[N];
bool chk(int d) {
multiset<int> st;
fo(i,1,m) st.insert(b[i]);
fo(i,1,n) {
auto it = st.lower_bound(a[i]-d);
if (it!=st.end()&&abs(*it - a[i]) <= d) st.erase(it);
else return 0;
}
return 1;
}
void solve() {
cin >> n >> m;
fo(i,1,n) cin >> a[i];
fo(i,1,m) cin >> b[i];
sort(a+1, a+n+1); sort(b+1, b+m+1);
if (n>m) {
fo(i,1,n) swap(a[i], b[i]);
swap(n, m);
}
int l=0, r=1e9, mid, res=1e9;
while (l<=r) {
mid=(l+r)/2;
if (chk(mid)) res=mid, r=mid-1;
else l=mid+1;
}
cout << res;
}
signed main() {
cin.tie(0)->sync_with_stdio(0);
if (fopen("A.inp", "r"))
freopen("A.inp", "r", stdin);
solve();
}
