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

template <class T, class F>
T LowerBound(T i0, T i1, F f) {
    while (i0 < i1) {
        T i = i0 + (i1 - i0) / 2;
        if (f(i)) i1 = i; else i0 = i + 1;
    }
    return i0;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n, p;
    ll k;
    cin >> n >> k >> p;

    vector<int> a(n), b(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    for (int i = 0; i < n; i++) {
        cin >> b[i];
    }
    sort(b.begin(), b.end());

    vector<int> q(p + 1);
    int i = 0;
    for (int j = 0; j <= p; j++) {
        while (i < n && b[i] < j) i++;
        q[j] = i;
    }

    auto c = LowerBound<int>(0, p, [&](auto c) {
        ll l = 0;
        for (const auto &a1 : a) {
            int m = q[p - a1];
            int i0 = c - a1 + 1;
            i0 = clamp(i0, 0, p);
            l += q[i0] - 0;
            int i1 = c + p - a1 + 1;
            i1 = clamp(i1, 0, p);
            l += q[i1] - m;
        }
        //cout << c << ' ' << l << endl;
        return l >= k; // c以下の数がk個以上になった初めての数
    });
    cout << c << endl;

    return 0;
}