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

int main()
{
    int64_t n, k, p;
    cin >> n >> k >> p;
    vector<int64_t> a(n), b(n);
    for (auto &&x : a)
    {
        cin >> x;
    }
    for (auto &&x : b)
    {
        cin >> x;
    }
    sort(a.begin(), a.end());
    sort(b.begin(), b.end());

    auto f = [&](int64_t r)
    {
        int64_t res = 0;
        for (auto &&x : a)
        {
            res += lower_bound(b.begin(), b.end(), r - x) - b.begin();
        }
        return res;
    };

    int64_t l = 0, r = p;
    while (r - l > 1)
    {
        int64_t mid = (l + r) / 2;
        if (f(mid + p) - f(p) + f(mid) < k)
        {
            l = mid;
        }
        else
        {
            r = mid;
        }
    }
    cout << l << endl;
    return 0;
}