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

ll n,k,p;
ll A[100010],B[100100],C[200200];

bool f(ll x){
  ll cnt=0;
  rep(i,n){
    cnt+=upper_bound(C,C+2*n,p-A[i]+x)-lower_bound(C,C+2*n,p-A[i]);
  }
  if(cnt>=k) return true;
  else return false;
}
 
int main(){
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  
  cin>>n>>k>>p;
  rep(i,n) cin>>A[i];
  rep(i,n) cin>>B[i];
  sort(A,A+n);
  sort(B,B+n);
  rep(i,n){
    C[i]=B[i],C[i+n]=B[i]+p;
  }
  
  ll ng=-1,ok=p+1;
  while(ok-ng>1){
    ll mid=(ng+ok)/2;
    if(f(mid)) ok=mid;
    else ng=mid;
  }
  cout<<ok<<endl;
  
  return 0;
}