#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<ll,ll> P;
typedef modint1000000007 mint;
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define rrep(i,a,b) for(ll i=a;i>=b;i--)
const ll inf=1e18;
ll n,k,p;
ll a[100005],b[100005];
int main(void){
    cin.tie(0);
    ios::sync_with_stdio(0);
    cin>>n>>k>>p;
    rep(i,0,n) cin>>a[i];
    rep(i,0,n) cin>>b[i];
    sort(a,a+n);
    sort(b,b+n);
    ll l=0,r=p-1;
    while(r-l>1){
        ll m=(l+r)/2;
        ll cnt=0;
        rep(i,0,n){
            ll I=lower_bound(b,b+n,m-a[i]+1)-b;
            ll J=lower_bound(b,b+n,p-a[i])-b;
            ll K=lower_bound(b,b+n,p+m-a[i]+1)-b;
            cnt+=I+(K-J);
        }
        if(cnt>=k){
            r=m;
        }else{
            l=m;
        }
    }
    cout<<r<<endl;
}