#include "bits/stdc++.h"
using namespace std;
long long n, m;
const long long MXN = 100005;
long long a1[MXN], a2[MXN];
bool works(long long x) {
long long lpt = 0;
long long rpt = 0;
for (long long i=0; i<n; i++) {
long long at = a1[i];
long long mxr = at + x;
long long mnr = at - x;
while (rpt < m && a2[rpt] <= mxr) {
rpt++;
}
while (lpt < m && a2[lpt] < mnr) {
lpt++;
}
if (lpt == rpt) {
return false;
}
lpt++;
}
return true;
}
int main() {
cin >> n >> m;
if (n < m) {
for (long long i=0; i<n; i++) {
cin >> a1[i];
}
for (long long i=0; i<m; i++) {
cin >> a2[i];
}
}
else {
for (long long i=0; i<n; i++) {
cin >> a2[i];
}
for (long long i=0; i<m; i++) {
cin >> a1[i];
}
swap(n, m);
}
sort(a1, a1+n); sort(a2, a2+m);
long long low = 0;
long long high = INT_MAX;
while (low + 1 < high) {
long long mid = (low + high) / 2;
bool res = works(mid);
if (res) {
high = mid;
}
else {
low = mid;
}
}
if (works(low)) {
cout << low << endl;
}
else {
cout << high << endl;
}
}
