#include <bits/stdc++.h>
using namespace std;
#define int long long
using vec_int = vector<int>;
// using P = pair<int,int>;
using ll = long long;
#define rep(i, n) for(int i = 0; i < (int)(n); i++)

int calc(vec_int &imos, int left, int right){
    if(left==0)return imos.at(right);
    return imos.at(right)-imos.at(left-1);
}

int count(vec_int &A, vec_int &imos, int mid, int P){
    int num = 0;
    int N = A.size();
    for(int i=0;i<N;i++){
        int left = (P-A.at(i))%P;
        int right = (P+mid-A.at(i))%P;
        if(left<=right){
            num += calc(imos, left, right);
        }else{
            num += calc(imos, left, P-1);
            num += calc(imos, 0, right);
        }
    }
    return num;
}

signed main(){
    int N, K, P; cin>>N>>K>>P;
    vec_int A(N), B(N); 
    rep(i,N)cin>>A.at(i);
    rep(i,N)cin>>B.at(i);

    vec_int imos(P, 0);
    rep(i,N){
        imos.at(B.at(i))++;
    }
    for(int i=1;i<P;i++)imos.at(i) += imos.at(i-1);

    int left = -1; //K以下値
    int right = P-1; //K番目より大きい値

    while(right>left+1){
        int mid = (right+left)/2;
        int num = count(A, imos, mid, P);
        if(num<K){
            left = mid;
        }else{
            right = mid;
        }
    }
    cout<<right<<endl;








   return 0;
}