#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i,n)for (int i = 0; i < int(n); ++i)
#define rrep(i,n)for (int i = int(n)-1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template<class T> void chmax(T& a, const T& b) {a = max(a, b);}
template<class T> void chmin(T& a, const T& b) {a = min(a, b);}
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, p;
    ll k;
    cin >> n >> k >> p;
    VI a(n), b(n);
    rep(i, n) cin >> a[i];
    rep(i, n) cin >> b[i];
    sort(all(a));
    VI s(p + 1);
    for(int x: b) s[x]++;
    int now = 0;
    rep(i, p + 1) {
        int nxt = now + s[i];
        s[i] = now;
        now = nxt;
    }
    int l = -1, r = p - 1;
    while(r - l > 1) {
        int c = (l + r) / 2;
        ll cnt = 0;
        for(int x: a) {
            // x + y <= c
            // y <= c - x
            int r1 = clamp(c - x + 1, 0, p);
            cnt += s[r1];
            // p <= x + y <= p + c
            // p - x <= y <= p + c - x
            int l2 = clamp(p - x, 0, p), r2 = clamp(p + c - x + 1, 0, p);
            cnt += s[r2] - s[l2];
        }
        if (cnt >= k) {
            r = c;
        } else {
            l = c;
        }
    }
    cout << r << endl;
}