#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<ll, ll> p_ll;

template<class T>
void debug(T itr1, T itr2) { auto now = itr1; while(now<itr2) { cout << *now << " "; now++; } cout << endl; }
#define repr(i,from,to) for (int i=(int)from; i<(int)to; i++)
#define all(vec) vec.begin(), vec.end()
#define rep(i,N) repr(i,0,N)
#define per(i,N) for (int i=(int)N-1; i>=0; i--)

const ll MOD = pow(10,9)+7;
const ll LLINF = pow(2,61)-1;
const int INF = pow(2,30)-1;

vector<ll> fac;
void c_fac(int x=pow(10,6)+10) { fac.resize(x,true); rep(i,x) fac[i] = i ? (fac[i-1]*i)%MOD : 1; }
ll inv(ll a, ll m=MOD) { ll b = m, x = 1, y = 0; while (b!=0) { int d = a/b; a -= b*d; swap(a,b); x -= y*d; swap(x,y); } return (x+m)%m; }
ll nck(ll n, ll k) { return fac[n]*inv(fac[k]*fac[n-k]%MOD)%MOD; }
ll gcd(ll a, ll b) { if (a<b) swap(a,b); return b==0 ? a : gcd(b, a%b); }
ll lcm(ll a, ll b) { return a/gcd(a,b)*b; }

int main() {
  ll N, L; cin >> N  >> L;
  set<ll> x, y; set<ll, greater<ll>> ry;
  rep(i,N) { ll tx; cin >> tx; x.insert(tx); }
  rep(i,N) { ll ty; cin >> ty; y.insert(ty); ry.insert(ty); }

  ll now = *x.begin(), count = 0; x.erase(now);
  rep(i,N-1) {
    cout << i << endl;
    auto typos = y.upper_bound(now); if (typos==y.end()) { count++; typos = y.begin(); }
    auto xpos = x.upper_bound(*typos); if (xpos==x.end()) { count++; xpos = x.begin(); }
    auto ypos = ry.upper_bound(*xpos); if (ypos==ry.end()) ypos = ry.begin();
    // cout << now << "->" << *typos << " " << *ypos << " " << *xpos << " " << count << endl;
    now = *xpos;
    x.erase(xpos); y.erase(*ypos); ry.erase(ypos);
  }
  
  ll last = *y.begin();
  count += now>last; now = last;

  ll result = now + L * count;
  cout << result << endl;
  return 0;
}