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

struct iofast_t {
    iofast_t() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} iofast;

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return std::vector(arg, init);
    else return std::vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }

int main() {
    int64_t n, k, p; cin >> n >> k >> p;
    auto a = vec<int>(uns, n);
    auto b = vec<int>(uns, n);
    for (auto &e : a) cin >> e;
    for (auto &e : b) cin >> e;
    sort(begin(a), end(a));
    sort(begin(b), end(b));

    auto count = [&](int x) {
        int64_t ans = 0;
        for (auto v : a) {
            auto last = lower_bound(begin(b), end(b), p - v);
            ans += distance(begin(b), upper_bound(begin(b), last, x - v));
            ans += distance(last, upper_bound(last, end(b), x - v + p));
        }
        return ans;
    };

    int l = -1, r = p;
    while (1 < r - l) {
        int m = l + (r - l) / 2;

        if (count(m) < k) {
            l = m;
        }
        else {
            r = m;
        }
    }

    cout << r << endl;
}