#include<bits/stdc++.h>
#define rep(i,a,...) for(int i = (a)*(strlen(#__VA_ARGS__)!=0);i<(int)(strlen(#__VA_ARGS__)?__VA_ARGS__:(a));++i)
#define per(i,a,...) for(int i = (strlen(#__VA_ARGS__)?__VA_ARGS__:(a))-1;i>=(int)(strlen(#__VA_ARGS__)?(a):0);--i)
#define foreach(i, n) for(auto &i:(n))
#define all(x) (x).begin(), (x).end()
#define bit(x) (1ll << (x))
#define lambda(RES_TYPE, ...) (function<RES_TYPE(__VA_ARGS__)>)[&](__VA_ARGS__) -> RES_TYPE
#define method(FUNC_NAME, RES_TYPE, ...) function<RES_TYPE(__VA_ARGS__)> FUNC_NAME = lambda(RES_TYPE, __VA_ARGS__)
using namespace std;
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
//const ll MOD = (ll)1e9+7;
const ll MOD = 998244353;
const int INF = (ll)1e9+7;
const ll INFLL = (ll)1e18;
template<class t>
using vvector = vector<vector<t>>;
template<class t>
using vvvector = vector<vector<vector<t>>>;
template<class t>
using priority_queuer = priority_queue<t, vector<t>, greater<t>>;
template<class t, class u> bool chmax(t &a, u b){if(a<b){a=b;return true;}return false;}
template<class t, class u> bool chmin(t &a, u b){if(a>b){a=b;return true;}return false;}
#ifdef DEBUG
#define debug(x) cout<<"LINE "<<__LINE__<<": "<<#x<<" = "<<x<<endl;
#else
#define debug(x) (void)0
#endif

namespace templates{
  ll modpow(ll x, ll b){
    ll res = 1;
    while(b){
      if(b&1)res = res * x % MOD;
      x = x * x % MOD;
      b>>=1;
    }
    return res;
  }

  ll modinv(ll x){
    return modpow(x, MOD-2);
  }

  bool was_output = false;
  template<class t>
  void output(t a){
    if(was_output)cout << " ";
    cout << a;
    was_output = true;
  }
  void outendl(){
    was_output = false;
    cout << endl;
  }
  ll in(){
    ll res;
    scanf("%lld", &res);
    return res;
  }

  template<class t>
  istream& operator>>(istream&is, vector<t>&x){
    for(auto &i:x)is >> i;
    return is;
  }

  template<class t, class u>
  istream& operator>>(istream&is, pair<t, u>&x){
    is >> x.first >> x.second;
    return is;
  }

  template<class t>
  t in(){
    t res; cin >> res; return res;
  }

  template<class t>
  void out(t x){
    cout << x;
  }

  template<class t>
  vector<t> sorted(vector<t> line,function<bool(t,t)> comp=[](t a,t b){return a<b;}){
    sort(line.begin(),line.end(),comp);
    return line;
  }

  template<class t>
  vector<t> reversed(vector<t> line){
    reverse(line.begin(),line.end());
    return line;
  }
}

using namespace templates;

ll func(){
    int n = in();
    int L = in();
    vector<ll> start(n);
    vector<ll> goal(n);
    foreach(i,start)i=in();
    foreach(i,goal)i=in();
    vector<ll> x(n+1);
    vector<ll> y(n+1);
    x[0] = start[0]-1;
    y[0] = goal[0]-1;
    x.back() = L - start.back();
    y.back() = L - goal.back();
    rep(i,1,n){
        x[i] = start[i]-start[i-1]-1;
        y[i] = goal[i]-goal[i-1]-1;
    }
    int last = 0;
    ll res = 0;
    rep(i,n+1){
        while(last < n + 1 and x[last]==0)++last;
        if(y[i]==0)continue;
        ll sum = 0;
        int itr = last;
        while(sum < y[i]){
            sum += x[itr++];
        }
        if(sum != y[i])return -1;
        if(last < i and i < itr){
            res += i - last;
            res += itr - i - 1;
        }else{
            res += max(abs(i-last),abs(i-(itr-1)));
        }
        last = itr;
    }
    return res;
}

int main(){
    cout << func() << endl;
  return 0;
}

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

#define MAX 1000000010
using ll = long long;

int main(){
    ll N, C;
    cin >> N >> C;

    vector<pair<ll,ll>>event;

	for(int i=0;i<N;i++){
        ll a, b, c;
        cin >> a >> b >> c;
		event.push_back(make_pair(a,c));
		event.push_back(make_pair(b+1,-c));
	}

	sort(event.begin(), event.end());

	ll cost = 0;
    ll ans = 0;
    ll beforeday = 0;
    ll beforecost = 0;

    for(auto day : event){
        ans += beforecost * (day.first - beforeday);
        cost += day.second; 
        beforecost = min(cost, C);
        beforeday = day.first;
    }

    cout << ans;
}