#include <iostream>
#include <algorithm>
#include <cmath>
#include <tuple>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#define flush fflush(stdout)
#define endl '\n'
#define all(v) v.begin(), v.end()
#define pf(dans) printf("%.12lf", dans)
#define pfn(dans) pf(dans); cout << endl;
using namespace std;
//using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;
typedef pair<ll, ll> Pl;
const int mod1 = (int)1e9 + 7, mod2 = (int)998244353;
const int INF = (int)1e9 + 10;
const ll LINF = (ll)1e18 + 10;
const int di[8] = {1, 0, -1, 0, 1, 1, -1, -1}, dj[8] = {0, 1, 0, -1, -1, 1, -1, 1};

#define rep0(i, n) for (i = 0; i < n; i++)
#define rep1(i, a, b) for (i = a; i < b; i++)
#define reprev(i, n) for (i = n - 1; i >= 0; i--)

template <typename T>
T my_abs(T x){
    return (x >= 0)? x : -x;
}

template <typename T>
void chmax(T &a, T b){
    a = max(a, b);
}

template <typename T>
void chmin(T &a, T b){
    a = min(a, b);
}

ll gcd(ll a, ll b){
    if (a > b) return gcd(b, a);
    if (a == 0) return b;
    return gcd(b % a, a);
}

bool incld_bit(ll bit, int i){
    return ((bit>>i) & 1) == 1;
}

// --------------------------------------------------------------------------------

int main(void){
    int i, j;
    int n, p;
    ll k;
    int a[100003], b[100003];
    
    cin >> n >> k >> p;
    rep0(i, n){
        cin >> a[i];
    }
    rep0(i, n){
        cin >> b[i];
    }

    sort(a, a + n);
    sort(b, b + n);

    int l, r, mid;
    int *p1, *p2, *p3, *p4;
    ll s;
    l = -1;
    r = p;
    while (r - l > 1){
        mid = (l + r) / 2;
        s = 0;
        rep0(i, n){
            p1 = b;
            p2 = upper_bound(b, b + n, mid - a[i]);
            p3 = lower_bound(b, b + n, p - a[i]);
            p4 = upper_bound(b, b + n, p + mid - a[i]);
            s += p2 - p1 + p4 - p3;
        }
        if (s >= k){
            r = mid;
        }else{
            l = mid;
        }
    }

    cout << r << endl;

    return 0;
}