#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;

int main()
{
    int n; ll k;
    int p;
    cin>>n>>k>>p;
    int a[100010], b[100010];
    for(int i=0; i<n; i++){
        cin>>a[i];
    }
    for(int i=0; i<n; i++){
        cin>>b[i];
    }
    sort(a, a+n); sort(b, b+n);
    int l=-1, r=p-1;
    while(r-l>1){
        int m=(l+r)/2;
        ll c=0;
        for(int i=0; i<n; i++){
            int t=lower_bound(b, b+n, m+1-a[i])-b;
            c+=t;
            int t2=lower_bound(b, b+n, p-a[i])-b;
            int t3=lower_bound(b, b+n, m+p+1-a[i])-b;
            c+=t3-t2;
        }
        if(c>=k) r=m;
        else l=m;
    }
    cout<<r<<endl;
    return 0;
}