#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;
const int MAXN = (int)1e5 + 7;
const int infint = (int)1e9;
const ll inf = (ll)1e18;
int n, m, a[MAXN], b[MAXN];
bool check(ll mid)
{
if(n <= m)
{
int last = m;
for (int j = n - 1; j >= 0; j--)
{
int r = upper_bound(b, b + m, a[j] + mid) - b - 1;
int l = lower_bound(b, b + m, a[j] - mid) - b;
if(l > r)
return 0;
if(l > last - 1)
return 0;
last = min(r, last - 1);
}
return 1;
}
else
{
int last = n;
for (int j = m - 1; j >= 0; j--)
{
int r = upper_bound(a, a + n, b[j] + mid) - a - 1;
int l = lower_bound(a, a + n, b[j] - mid) - a;
if(l > r)
return 0;
if(l > last - 1)
return 0;
last = min(r, last - 1);
}
return 1;
}
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin >> n >> m;
for (int i = 0; i < n; i++)
cin >> a[i];
for (int i = 0; i < m; i++)
cin >> b[i];
sort(a, a + n);
sort(b, b + m);
/*for (int i = 0; i < n; i++)
cout << a[i] << " ";
cout << endl;
for (int i = 0; i < m; i++)
cout << b[i] << " ";
cout << endl;*/
ll l = -1, r = infint + 1;
while(r - l > 1)
{
ll mid = (l + r) >> 1;
if(check(mid))
r = mid;
else
l = mid;
}
cout << r;
}
