#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (int)n; i++)
using ll = long long;

int main(){
  ll n, k, p;
  cin >> n >> k >> p;
  vector<ll> a(n), b(n);
  rep(i,n) cin >> a[i];
  rep(i,n) cin >> b[i];
  sort(a.begin(),a.end());
  sort(b.begin(),b.end());
  ll l = -1, r = p-1;
  while(r-l > 1) {
    ll m = (l + r)/2;
    ll cnt = 0;
    rep(i,n) {
      cnt += upper_bound(b.begin(),b.end(),m-a[i]) - lower_bound(b.begin(),b.end(),-a[i]);
      cnt += upper_bound(b.begin(),b.end(),p+m-a[i]) - lower_bound(b.begin(),b.end(),p-a[i]);;
    }
    if(cnt < k) l = m;
    else r = m;
  }
  cout << r << endl;
  return 0;
}