#include <bits/stdc++.h>
using namespace std;
int main()
{
    int N, M;
    cin >> N >> M;
    vector<int> T(M);
    int S;
    multiset<int> st;
    for (int i = 0; i < N; ++i)
    {
        cin >> S;
        st.insert(S);
    }
    st.insert(2e9 + 10);
    int finish = 0;
    multiset<int> st2 = st;
    for (int i = 0; i < M; ++i)
    {
        cin >> T[i];
        auto itr = st.lower_bound(T[i]);
        if (*itr == 2e9 + 10)
            break;
        st.erase(itr);
        finish++;
    }
    if (finish == 0)
    {
        cout << 0 << endl;
        return 0;
    }
    int l = 0, r = 1e9;
    int md;
    while (r - l > 1)
    {
        md = (l + r) / 2;
        st = st2;
        bool check = true;
        for (int i = 0; i < finish; ++i)
        {
            auto itr = st.lower_bound(T[i] + md);
            if (*itr == 2e9 + 10)
            {
                check = false;
                break;
            }
            st.erase(itr);
        }
        if (check)
            l = md;
        else
            r = md;
    }
    cout << l << endl;
    return 0;
}