#include<bits/stdc++.h>
#include <atcoder/all>
#define ll long long int
#define vec vector<ll>
#define mat vector<vector<ll>>
#define pll pair<ll,ll>
#define count __builtin_popcountll

using namespace std;
using namespace atcoder;
//using mint = modint1000000007;

const ll mod=1000000007;//998244353;
const ll inf=1000000000000000000;
ll dx4[4]={1,0,-1,0};
ll dy4[4]={0,-1,0,1};
ll dx8[8]={1,0,-1,1,-1,1,0,-1};
ll dy8[8]={1,1,1,0,0,-1,-1,-1};

int main(){
  cout << fixed << setprecision(15);

  ll n,k,p;
  cin >> n >> k >> p;
  vec a(n),b(n);
  for(ll i=0;i<n;i++)cin >> a[i];
  for(ll i=0;i<n;i++)cin >> b[i];
  for(ll i=0;i<n;i++){
    a[i]%=p;
    b[i]%=p;
  }
  


  sort(a.begin(),a.end());
  sort(b.begin(),b.end());


  vec s(p);
  for(ll i=0;i<n;i++){
    s[b[i]]++;
  }
  for(ll i=0;i<p-1;i++){
    s[i+1]+=s[i];
  }


  // ll s=0;
  //   for(ll i=0;i<n;i++){
  //     if(a[i]<2){
  //       s+=upper_bound(b.begin(),b.end(),2-a[i])-b.begin()-1;
  //       s+=n-(upper_bound(b.begin(),b.end(),p-a[i])-b.begin());
  //     }
  //     else{
  //       s+=upper_bound(b.begin(),b.end(),(2-a[i]+p)%p)-lower_bound(b.begin(),b.end(),p-a[i]);
  //     }
  //     cout << s << endl;
  //   }
  //   cout << s << endl;


  ll l=0,r=p,h=(r+l)/2;

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

  cout << r << endl;
  

  return 0;
}