#include <bits/stdc++.h>
using namespace std;
int main(){
    int N;
    long long K;
    long long P;
    cin >> N >> K >> P;
    vector<long long> 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());
    int ub = P, lb = -1;
    while(ub - lb > 1){
        int mid = (ub + lb) / 2;
        long long cnt = 0;
        for(int i = 0; i < N; i++){
            if(mid < A[i]){
                int ind = upper_bound(B.begin(), B.end(), mid + P - A[i]) - lower_bound(B.begin(), B.end(), P - A[i]);
                cnt += ind;
            }
            else{
                int ind = upper_bound(B.begin(), B.end(), mid + P - A[i]) - lower_bound(B.begin(), B.end(), P - A[i]);
                int id = upper_bound(B.begin(), B.end(), mid - A[i]) - B.begin();
                cnt += ind;
                cnt += id;
            }
        }
        if(cnt >= K) ub = mid;
        else lb = mid;
    }
    cout << ub << endl;
}