#include<bits/stdc++.h>
using namespace std;
#define ALL(x) begin(x),end(x)
#define rep(i,n) for(int i=0;i<(n);i++)
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define mod 1000000007
using ll=long long;
const int INF=1000000000;
const ll LINF=1001002003004005006ll;
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
// ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return true;}return false;}

struct IOSetup{
    IOSetup(){
        cin.tie(0);
        ios::sync_with_stdio(0);
        cout<<fixed<<setprecision(12);
    }
} iosetup;

template<typename T>
ostream &operator<<(ostream &os,const vector<T>&v){
    for(int i=0;i<(int)v.size();i++) os<<v[i]<<(i+1==(int)v.size()?"":" ");
    return os;
}
template<typename T>
istream &operator>>(istream &is,vector<T>&v){
    for(T &x:v)is>>x;
    return is;
}

signed main(){
    int N,P;ll K;cin>>N>>K>>P;
    vector<int> A(N),B(P,0);
    cin>>A;
    rep(i,N){
        int x;cin>>x;
        B[x]++;
    }

    vector<int> S(P+1,0);
    rep(i,P) S[i+1]=S[i]+B[i];

    auto f=[&](ll m){
        ll ret=0;
        for(auto &x:A){
            {
                ll up=m-x;
                if(up>=0) ret+=S[up+1];
            }
            {
                int lw=P-x,hi=P+m-x;
                chmin(hi,P-1);
                ret+=S[hi+1]-S[lw];
            }
        }
        return ret;
    };

    ll lw=0,hi=P-1,res;
    while(lw<=hi){
        ll mid=(lw+hi)/2;

        if(f(mid)>=K) res=mid,hi=mid-1;
        else          lw=mid+1;
    }
    cout<<res<<endl;
    return 0;
}