#include <bits/stdc++.h>
#define el '\n'
#define FNAME "ffuel"
#define allof(x) x.begin(),x.end()
#define allof1(x) x.begin()+1,x.end()
#define mset(x,n) memset(x,(n),sizeof(x))
using namespace std;
const long long MOD = (long long) 1e9 + 7;
template<class X,class Y> bool minimize(X &a,Y b){ if (a>b) {a=b; return true;} return false;}
template<class X,class Y> bool maximize(X &a,Y b){ if (a<b) {a=b; return true;} return false;}
void setup(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
if (fopen(FNAME".inp","r")){
freopen(FNAME".inp","r",stdin);
freopen(FNAME".out","w",stdout);
}
}
const int INF = 1e9 + 15092007;
struct Station{
int pos,refill,thres;
Station(int p,int a,int b):pos(p),refill(a),thres(b) {}
bool operator < (const Station &other) const{
if (pos == other.pos)
return (refill < other.refill or (refill==other.refill and thres < other.thres));
return pos < other.pos;
}
inline void unpack(int &p,int &a,int &b) const{
p = pos;
a = refill;
b = thres;
}
};
struct SegmentTree{
struct Node{
long long deltaSum,minPref;
Node():deltaSum(0),minPref(0) {}
Node(long long s,long long p):deltaSum(s),minPref(p) {}
static Node merge(const Node &A,const Node &B){
return Node(A.deltaSum + B.deltaSum,min(A.minPref,A.deltaSum + B.minPref));
}
};
int n;
vector<Node> st;
SegmentTree(int N):n(N){
st.resize(4 * n + 4);
}
void update(int node,int l,int r,int pos,long long val){
if (l == r){
st[node] = Node(val,val);
return;
}
int mid = (l+r)>>1;
if (pos <= mid) update(2 * node,l,mid,pos,val);
else update(2 * node + 1,mid+1,r,pos,val);
st[node] = Node::merge(st[2*node],st[2*node+1]);
}
void update(int pos,long long val){
update(1,1,n,pos,val);
}
inline long long getMin(){
return st[1].minPref;
}
};
int n,D;
vector<Station> station;
vector<int> Pos,Refill,Threshold;
void init(){
cin>>n>>D;
for (int i=0;i<n;i++){
int p,a,b; cin>>p>>a>>b;
station.emplace_back(p,a,b);
}
sort(allof(station));
Pos.assign(n + 2, 0);
Refill.assign(n + 2, 0);
Threshold.assign(n + 2, INF);
for (int i = 0; i < n; i++)
station[i].unpack(Pos[i+1],Refill[i+1],Threshold[i+1]);
Pos[n + 1] = D;
}
void sol(){
SegmentTree st(n + 2);
st.update(n+1,-D);
set<int> processing;
processing.insert(0); processing.insert(n+1);
vector<int> order(n); iota(allof(order),1);
sort(allof(order),[&](int i,int j){
return Threshold[i] > Threshold[j];
});
long long res = D;
for (int l = 0; l < n; ){
int r = l;
while (r + 1 < n and Threshold[order[l]] == Threshold[order[r+1]]) r++;
for (int i = l; i <= r; i++){
int p = order[i];
processing.insert(p);
set<int>::iterator it = processing.find(p);
set<int>::iterator prv = prev(it), nxt = next(it);
st.update(p, Refill[*prv] - (Pos[p] - Pos[*prv]));
st.update(*nxt, Refill[p] - (Pos[*nxt] - Pos[p]));
}
if (st.getMin() + Threshold[order[l]] >= 0) minimize(res,-st.getMin());
l = r + 1;
}
cout<<res;
}
int main(){
setup();
init();
sol();
}
