#include <bits/stdc++.h>
#include <atcoder/all>
#define ll long long int
#define INF 1000000000000000000
using namespace atcoder;
using namespace std;

int main(void){
  ll n, k, p;
  cin >> n >> k >> p;
  vector<ll> a(n);
  for (int i = 0; i < n; i++){
    cin >> a[i];
  }
  vector<ll> b(n);
  for (int i = 0; i < n; i++){
    cin >> b[i];
  }
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());

  ll l = 0, r = p, m;
  while (l + 1 < r){
    m = (l + r)/2;
    ll t = 0;
    for (ll i = 0; i < n; i++){
      t += lower_bound(b.begin(), b.end(), m-a[i]) - b.begin();
      t += lower_bound(b.begin(), b.end(), p+m-a[i]) - lower_bound(b.begin(), b.end(), p-a[i]);
    }
    if (t >= k)
      r = m;
    else
      l = m;
  }
  cout << r-1 << endl;

  return 0;
}