#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int aps(int a) {
    return a < 0 ? -a : a;
}

int main() {
    int n;
    cin >> n;
    vector<int> a(n);
    for(int &x : a) cin >> x;

    int m;
    cin >> m;
    vector<int> b(m);
    for(int &x : b) cin >> x;

    int i = 0;
    int j = 0;

    sort(begin(a), end(a));
    sort(begin(b), end(b));

    int aps_raz = aps(a[i] - b[j]);
    int novo_resenje;
    while(i < n && j < m) {
        novo_resenje = aps(a[i] - b[j]);
        if(novo_resenje < aps_raz) aps_raz = novo_resenje;

        if(a[i] < b[j]) i++;
        else j++;
    }
    cout << aps_raz << endl;
}