#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>
#include <atcoder/convolution>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    ll n, k, p; cin >> n >> k >> p;
    vector<ll> 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(a.begin(), a.end());
    sort(b.begin(), b.end());
    auto sect_elements = [&](int l, int r)->int{
        if(r < l) return 0;
        if(r < 0) return 0;
        chmax(l, 0);
        int ans = upper_bound(b.begin(), b.end(), r)-lower_bound(b.begin(), b.end(), l);
        // cout << l << ',' << r << ' ' << ans << endl;
        return ans;
    };
    auto calc = [&](int c){
        ll ans = 0;
        for(int i = 0; i < n; i++){
            ans += sect_elements(-a[i], c-a[i]);
            ans += sect_elements(p-a[i], p+c-a[i]);
        }
        return ans;
    };
    if(calc(0) >= k){
        cout << 0 << endl;
        return 0;
    }
    int l = 0, r = p-1;
    while(r-l > 1){
        int c = (l+r)/2;
        if(calc(c) < k) l = c;
        else r = c;
    }
    cout << r << endl;
}