#include <bits/stdc++.h>
using namespace std;

int binSearch(int used, vector<int>& a, int target) {
    int left = -1;
    int right = used;
    while (left < right - 1) {
        int mid = (left + right) / 2;
        if (a[mid] <= target) {
            left = mid;
        } else {
            right = mid;
        }
    }
    return left;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    map<int, int> map_;
    int n, m;
    cin >> n >> m;
    int INF = INT_MAX / 2;
    map_[INF] = -1;
    vector<int> a(n);
    vector<int> t(m);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        if (map_.find(a[i]) == map_.end()) {
            map_[a[i]] = 0;
        }
        map_[a[i]] = map_[a[i]] + 1;
    }

    int max_ = 0;
    for (int i = 0; i < m; i++) {
        cin >> t[i];
    }

    // 貪欲にやるのが最大にできそう
    for (int i = 0; i < m; i++) {
        auto it = map_.lower_bound(t[i]);
        if (it == map_.end()) break;
        int c = it->first;
        if (c == INF) break;
        max_ = i + 1;
        map_[c] = map_[c] - 1;
        if (map_[c] == 0) map_.erase(c);
    }

    vector<int> l;
    for (int i = 0; i < max_; i++) {
        l.push_back(t[i]);
    }
    sort(l.begin(), l.end(), greater<int>());
    sort(a.begin(), a.end());

    int left = -1;
    int right = 1000000001;
    while (left < right - 1) {
        int mid = (left + right) / 2;
        int used = n;
        bool ok = true;
        for (int i = 0; i < max_; i++) {
            int ind = binSearch(used, a, l[i] + mid);
            if (ind == -1 || a[ind] < l[i]) {
                ok = false;
                break;
            }
            used = ind;
        }
        if (ok) {
            right = mid;
        } else {
            left = mid;
        }
    }

    cout << right;
    return 0;
}