#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;
typedef long long ll;
ll a[100010];
vector<ll> b;
int main(){
    ll i,n,k,p; cin >> n >> k >> p;
    for(i=0;i<n;i++) cin >> a[i];
    for(i=0;i<n;i++){
        ll x; cin >> x; b.push_back(x);
    }
    sort(b.begin(),b.end());
    ll l = -1,r = p;
    while(r - l>1){
        //cout << l << " " << r << endl;
        ll mid = (l + r)/2;
        ll num = 0;
        for(i=0;i<n;i++){
            if(a[i]<=mid) num += upper_bound(b.begin(),b.end(),mid - a[i]) - lower_bound(b.begin(),b.end(),0);
            num += upper_bound(b.begin(),b.end(),p + mid - a[i]) - lower_bound(b.begin(),b.end(),p - a[i]);
        }
        if(num>=k) r = mid;
        else l = mid;
    }
    cout << r << endl;
}