#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
long long n, k, p;
vector<long long> a, b;
bool solve(long long x) {
	long long sum = 0;
	for (int i = 0; i < n; i++) {
		long long l1 = x - a[i];
		auto itr = upper_bound(b.begin(), b.end(), l1);
		sum += int(itr - b.begin());
		long long l2 = p - a[i];
		long long r1 = p + x - a[i];
		auto itr1 = lower_bound(b.begin(), b.end(), l2);
		auto itr2 = upper_bound(b.begin(), b.end(), r1);
		sum += int(itr2 - itr1);
	}
	if (sum < k) {
		return true;
	}
	else {
		return false;
	}
}
int main() {
	cin >> n >> k >> p;
	long long a1, b1;
	for (int i = 0; i < n; i++) {
		cin >> a1;
		a.emplace_back(a1);
	}
	for (int i = 0; i < n; i++) {
		cin >> b1;
		b.emplace_back(b1);
	}
	sort(a.begin(), a.end());
	sort(b.begin(), b.end());
	long long l = -1, r = p;
	while (r - l > 1) {
		long long mid = (l + r) / 2;
		if (solve(mid)) {
			l = mid;
		}
		else {
			r = mid;
		}
	}
	cout << r << endl;
}