#pragma GCC optimize("O3")
#include<bits/stdc++.h> 
using namespace std;
using ll=long long;
using lll=__int128_t;
using P=pair<ll,ll>;
template<class T> using V=vector<T>; 
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
const ll inf=(1e18);
//const ll mod=998244353;
const ll mod=1000000007;
const vector<int> dy={-1,0,1,0},dx={0,-1,0,1};
ll GCD(ll a,ll b) {return b ? GCD(b,a%b):a;}
ll LCM(ll c,ll d){return c/GCD(c,d)*d;}
struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}} __init;
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 (a>b) { a=b; return 1; } return 0; }
template<class T>void debag(const vector<T> &a){cerr<<"debag :";for(auto v:a)cerr<<v<<" ";cerr<<"\n";}
template<class T>void print(const vector<T> &a){for(auto v:a)cout<<v<<" ";cout<<"\n";}

int main(){
      ll n,k,p;
      cin>>n>>k>>p;
      V<ll> a(n),b(n);
      for(int i=0;i<n;i++){
            cin>>a[i];
            a[i]%=p;
      }
      for(int i=0;i<n;i++){
            cin>>b[i];
            b[i]%=p;
            b.emplace_back(b[i]+p);
      }
      sort(all(b));
      ll l=-1,r=p-1;
      while(r-l>1){
            ll mid=(l+r)/2;
            ll res=0;
            for(int i=0;i<n;i++){
                  ll v=(mid-a[i]+p);
                  ll d=(p-a[i]);
                  res+=upper_bound(all(b),v)-lower_bound(all(b),d);
            }
            if(res>=k)r=mid;
            else l=mid;
      }
      cout<<r<<"\n";
}