#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[8]={-1,0,1,0,1,1,-1,-1};
const ll dx[8]={0,-1,0,1,1,-1,1,-1};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
int main(){
    ll n,k,p;cin >> n >> k >> p;
    vl a(n),b(n);rep(i,n)cin >> a[i];rep(i,n)cin >> b[i];
    sort(all(a));sort(all(b));
    ll ok=inf,ng=-1;//ok以下になる組み合わせがK以上ある
    while(ok-ng>1){
        ll mid=(ok+ng)/2;
        ll ret=0;
        rep(i,n){
            ret+=upper_bound(all(b),mid-a[i])-b.begin();
            ret+=upper_bound(all(b),mid-a[i]+p)-b.begin();
            ret-=lower_bound(all(b),p-a[i])-b.begin();
        }
        if(ret>=k)ok=mid;
        else ng=mid;
    }
    cout << ok <<endl;
}