#include <bits/stdc++.h>
template<class T> inline bool chmin(T&a, T b){if(a > b){a = b; return true;}else{return false;}}
template<class T> inline bool chmax(T&a, T b){if(a < b){a = b; return true;}else{return false;}}
#define ll long long
#define double long double
#define rep(i,n) for(int i=0;i<(n);i++)
#define REP(i,n) for(int i=1;i<=(n);i++)
#define mod (ll)(1e9+7)
#define inf (ll)(3e18+7)
#define eps (double)(1e-9)
#define pi (double) acos(-1)
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
using namespace std;

int main(){
    ll n, k, p;
    cin >> n >> k >> p;
    vector<ll> a(n), b(n);
    rep(i, n)cin >> a[i];
    rep(i, n)cin >> b[i];
    rep(i, n){a[i] %= p; b[i] %= p;}
    vector<ll> sum(p+1);
    rep(i, n)sum[b[i]+1]++;
    rep(i, p)sum[i+1] += sum[i];
    ll ok = 0, ng = p;
    //ok以下の要素がK個未満
    while(ng - ok > 1){
        ll mid = (ok + ng) / 2;
        ll cnt = 0;
        rep(i, n){
            cnt += sum[max(0LL, mid-a[i]+1)];
            cnt += sum[min(p, p-a[i]+mid+1)] - sum[max(0LL, p-a[i])];
        }
        if(cnt < k)ok = mid;
        else ng = mid;

    }
    cout << ok+1 << endl;
}