#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define MAX 1000000
#define MOD 1000000007
//#define INF 1000000000
#define INF 1000000000000000000

int main(){
  int N,P;
  ll K;
  cin>>N>>K>>P;
  vector<int> A(N),B(N);
  for(int i=0;i<N;i++){
    cin>>A[i];
  }
  for(int i=0;i<N;i++){
    cin>>B[i];
  }
  sort(A.begin(),A.end());
  sort(B.begin(),B.end());

  {
    int x=0;
    ll cnt=0;
    for(int i=0;i<N;i++){
      int k;
      k=upper_bound(B.begin(),B.end(),x-A[i])-B.begin();
      cnt+=(ll)k;
      //cout<<cnt<<" ";
      k=upper_bound(B.begin(),B.end(),x+P-A[i])-B.begin();
      cnt+=(ll)k;
      //cout<<k<<" ";
      //cout<<cnt<<" ";
      k=upper_bound(B.begin(),B.end(),P-1-A[i])-B.begin();
      cnt-=(ll)k;
      //cout<<P-1-A[i]<<endl;
      //cout<<cnt<<endl;
    }
    if(cnt>=K){
      cout<<0<<endl;
      return 0;
    }
  }

  int left=0;
  int right=P;
  while(left+1<right){
    int x=(left+right)/2;
    ll cnt=0;
    for(int i=0;i<N;i++){
      int k;
      if(A[i]+B[0]<=x){
        k=upper_bound(B.begin(),B.end(),x-A[i])-B.begin();
        cnt+=(ll)k;
      }
      k=upper_bound(B.begin(),B.end(),x+P-A[i])-B.begin();
      cnt+=(ll)k;
      k=upper_bound(B.begin(),B.end(),P-1-A[i])-B.begin();
      cnt-=(ll)k;
    }
    if(cnt>=K){
      right=x;
    }else{
      left=x;
    }
  }
  cout<<right<<endl;
}