#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int n, p; ll k; cin >> n >> k >> p;
  vector<int> a(n), b(n);
  REP(i, n) cin >> a[i];
  REP(i, n) cin >> b[i];
  sort(ALL(b));
  int lb = -1, ub = p - 1;
  while (ub - lb > 1) {
    int mid = (lb + ub) / 2;
    ll cnt = 0;
    REP(i, n) {
      if (a[i] <= mid) {
        cnt += upper_bound(ALL(b), mid - a[i]) - b.begin();
        if (a[i] > 0) cnt += b.end() - lower_bound(ALL(b), p - a[i]);
      } else {
        cnt += upper_bound(ALL(b), mid + p - a[i]) - lower_bound(ALL(b), p - a[i]);
      }
    }
    (cnt < k ? lb : ub) = mid;
  }
  cout << ub << '\n';
  return 0;
}