#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, a[N], b[N];
int cnt(int s){
if(s == 0) return 2e9;
int res = 0;
for(int i = s; i <= s + m - 1; i++){
res = max(res, abs(a[i] - b[i - s + 1]));
}
return res;
}
bool check(int val){
for(int i = 1; i <= n - m + 1; i++){
if(abs(a[i] - b[1]) <= val){
return cnt(i) <= val;
}
}
return 0;
}
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 + 1, a + n + 1);
sort(b + 1, b + m + 1);
int l = 0, r = 1e9, mid;
while(l <= r){
int mid = (l + r) >> 1;
if(check(mid)) r = mid - 1;
else l = mid + 1;
}
cout<<l;
}
