#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <vector>

#define mkp make_pair
#define mkt make_tuple
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define all(v) v.begin(), v.end()
using namespace std;
typedef long long ll;
const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
template <class T>
void chmin(T &a, const T &b) {
    if (a > b) a = b;
}
template <class T>
void chmax(T &a, const T &b) {
    if (a < b) a = b;
}

void solve() {
    int N;
    ll K;
    int P;
    cin >> N >> K >> P;
    vector<vector<int>> A(2, vector<int>(N));
    rep(k, 2) rep(i, N) cin >> A[k][i];

    vector<vector<ll>> num(2, vector<ll>(P, 0));
    rep(k, 2) rep(i, N) num[k][A[k][i]]++;
    vector<vector<ll>> sum(2, vector<ll>(P + 1, 0));
    rep(k, 2) {
        rep(i, P) sum[k][i + 1] = sum[k][i] + num[k][i];
    }

    auto judge = [&](int lim) -> bool {
        ll res = 0;
        rep(k, P) {
            ll tmp = 0;
            if (k <= lim) {
                tmp += sum[1][lim - k + 1];
                tmp += sum[1][P] - sum[1][P - k];
            } else {
                tmp += sum[1][min(P, P - k + lim + 1)] - sum[1][P - k];
            }
            res += num[0][k] * tmp;
            if (res >= K) return true;
        }
        return false;
    };

    int ok = P, ng = -1;
    while (abs(ok - ng) > 1) {
        int mid = (ok + ng) / 2;
        if (judge(mid))
            ok = mid;
        else
            ng = mid;
    }

    cout << ok << endl;
}

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

    solve();

    return 0;
}