#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main(){
  int n,p;
  ll k;
  cin>>n>>k>>p;
  vector<int> a(n),b(n);
  for(int &x:a){
    cin>>x;
    x%=p;
  }
  for(int &x:b){
    cin>>x;
    x%=p;
  }
  sort(a.begin(),a.end());
  sort(b.begin(),b.end());
  int lo=0,hi=p;
  while(hi-lo>1){
    int mid=(lo+hi)/2;
    ll cnt=0;
    int j1=n-1,j2=n-1,j3=n-1;
    for(int i=0;i<n;i++){
      while(j1>=0&&a[i]+b[j1]>=mid)j1--;
      while(j2>=0&&a[i]+b[j2]>=p)j2--;
      while(j3>=0&&a[i]+b[j3]>=p+mid)j3--;
      cnt+=j1+1+j3-j2;
    }
    if(cnt>=k)hi=mid;
    else lo=mid;
  }
  cout<<lo<<endl;
}