#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {
	cout << vars << " = [";
	string delim = "";
	(..., (cout << delim << values, delim = ", "));
	cout << "]" << " ";
}
ll n, k, p;
vector<ll>x, y, dp;
bool solve(ll mid) {
	ll ans = 0;
	for (ll i = 0; i < n; i++) {
		ans += dp[p + mid - x[i]] - dp[p - x[i] - 1];
		if (mid - x[i] >= 0) {
			ans += dp[mid - x[i]];
		}
	}
	return (ans >= k);
}
void solve() {
	cin >> n >> k >> p;
	x.resize(n);
	y.resize(n);
	dp.resize(2 * p + 1);
	dp.assign(2 * p + 1, 0);
	for (ll i = 0; i < n; i++) {
		cin >> x[i];
	}
	for (ll i = 0; i < n; i++) {
		cin >> y[i];
	}
	for (int i = 0; i < n; i++) {
		dp[y[i]]++;
	}
	for (ll i = 1; i <= 2 * p; i++) {
		dp[i] += dp[i - 1];
	}
	ll L = -1, R = p + 1;
	while (R - L > 1) {
		ll mid = (L + R) / 2;
		if (solve(mid))R = mid;
		else L = mid;
	}
	cout << R << endl;
}
int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	ll T;
	T = 1;
	//cin >> T;
	while (T--) {
		solve();
	}
}