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

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint1000000007 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

//defmodfact
const int COMinitMAX = 998244;
mint fact[COMinitMAX+1], factinv[COMinitMAX+1];

void modfact(){
	fact[0] = 1;
	for (int i=1; i<=COMinitMAX; i++){
		fact[i] = fact[i-1] * i;
	}
	factinv[COMinitMAX] = fact[COMinitMAX].inv();
	for (int i=COMinitMAX-1; i>=0; i--){
		factinv[i] = factinv[i+1] * (i+1);
	}
}

mint cmb(int a, int b){
	if (a<b || b<0) return mint(0);
	return fact[a]*factinv[b]*factinv[a-b];
}
//--------

// importbisect
template <typename T>
int bisect_left(vector<T> &X, T v){
	return lower_bound(X.begin(), X.end(), v) - X.begin();
}

template <typename T>
int bisect_right(vector<T> &X, T v){
	return upper_bound(X.begin(), X.end(), v) - X.begin();
}
// -----


int main(){
	int n; cin >> n;
	ll k; cin >> k;
	int p; cin >> p;
	vector<ll> a(n), b(n);
	rep(i,0,n){
		cin >> a[i];
	}
	rep(i,0,n){
		cin >> b[i];
	}
	sort(b.begin(), b.end());

	auto get = [&](ll y, ll l, ll r){
		return bisect_left(b, -y+r) - bisect_left(b, -y+l);
	};

	auto check = [&](ll x){
		ll tmp = 0;
		rep(i,0,n){
			tmp += get(a[i], 0, x);
			tmp += get(a[i], p, p+x);
		}
		return tmp < k;
	};
	
	ll ub = p;
	ll lb = 0;
	while (ub - lb > 1){
		ll targ = (ub + lb) / 2;
		if (check(targ)) lb = targ;
		else ub = targ;
	}

	cout << lb << '\n';
}