#include <bits/stdc++.h>
// #include <atcoder/modint>
#define rng(a) a.begin(),a.end()
#define rrng(a) a.rbegin(),a.rend()
#define INF 2000000000000000000
#define ll long long
#define ld long double
#define pll pair<ll, ll>
using namespace std;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll N, K, mod;
  cin >> N >> K >> mod;
  vector<ll> A(N), B(N);
  for (ll i = 0; i < N; ++i) {
    cin >> A.at(i);
    A.at(i) %= mod;
  }
  for (ll i = 0; i < N; ++i) {
    cin >> B.at(i);
    B.at(i) %= mod;
  }
  sort(rng(A));
  sort(rng(B));
  ll l = -1, r = mod - 1;
  while (l + 1 != r) {
    ll m = (l + r) / 2;
    ll cnt = 0;
    for (ll i = 0; i < N; ++i) {
      ll a = A.at(i);
      if (a <= m) {
        ll left = m - a;
        cnt += upper_bound(rng(B), left) - B.begin();
      }
      ll need = mod - a;
      ll cap_max = m + mod - a;
      cnt += upper_bound(rng(B), cap_max) - lower_bound(rng(B), need);
    }
    if (cnt >= K) {
      r = m;
    }
    else {
      l = m;
    }
  }
  cout << r << "\n";
}