#include <bits/stdc++.h>
using ll = long long;
using std::cin;
using std::cout;
using std::endl;
std::mt19937 rnd(std::chrono::steady_clock::now().time_since_epoch().count());
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const int inf = (int)1e9 + 7;
const long long INF = 1LL << 60;

void solve()
{
  ll n, K, P; cin >> n >> K >> P;
  std::vector<ll> a(n), b(n);
  for (int i = 0; i < n; ++i)
  {
    cin >> a[i];
  }
  for (int i = 0; i < n; ++i)
  {
    cin >> b[i];
  }
  std::sort(a.begin(), a.end());
  std::sort(b.begin(), b.end());
  ll lf = -1;
  ll rg = P - 1;
  while(rg - lf > 1)
  {
    ll mid = (lf + rg) >> 1;
    ll cnt = 0;
    for (int i = 0; i < n; ++i)
    {
      if(a[i] <= mid)
      {
        ll r = mid - a[i];
        cnt += std::upper_bound(b.begin(), b.end(), r) - b.begin();
      }
      {
        ll r = P - a[i];
        cnt += std::upper_bound(b.begin(), b.end(), r + mid) - std::lower_bound(b.begin(), b.end(), r);
      }
    }
    if(cnt < K)
    {
      lf = mid;
    }
    else
    {
      rg = mid;
    }
  }
  cout << rg << "\n";
}

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

  int kkt = 1; 
  // cin >> kkt;
  while(kkt--)
    solve();
  return 0;
}