#include <bits/stdc++.h>   using namespace std;   const int N = 100010;   set<pair<int, int> > s, e;   long long dp[N];   int l[N], r[N];   struct Point {     int x, h, k;     bool f;   } p[2 * N];   struct temp {     int h, k;   } q[N];   int m;   bool cmp1(const temp &a, const temp &b) { return a.h > b.h; }   bool cmp(const Point &a, const Point &b) {     if (a.x != b.x) return a.x < b.x;     if (a.f != b.f) return a.f;     return a.k < b.k;   }   vector<int> tran[N];   int main() {     set<pair<int, int> >::iterator it;     int n, t;     scanf( %d%d , &n, &t);     for (int i = 0; i < n; i++) {       int h;       scanf( %d%d%d , &h, &l[i + 1], &r[i + 1]);       p[m].x = l[i + 1], p[m].h = h, p[m].k = i + 1, p[m++].f = false;       p[m].x = r[i + 1], p[m].h = h, p[m].k = i + 1, p[m++].f = true;       q[i].h = h, q[i].k = i + 1;     }     l[0] = -(1 << 30), r[0] = (1 << 30);     l[n + 1] = -(1 << 30), r[n + 1] = (1 << 30);     q[n].h = t, q[n].k = 0;     q[n + 1].h = 0, q[n + 1].k = n + 1;     sort(p, p + m, cmp);     sort(q, q + n + 2, cmp1);     s.insert(make_pair(t, 0));     s.insert(make_pair(0, n + 1));     for (int i = 0; i < m; i++) {       if (p[i].f) {         it = s.find(make_pair(p[i].h, p[i].k));         if (it != s.end()) s.erase(it);       } else {         int a, b;         it = s.lower_bound(make_pair(p[i].h, 0));         a = it->second;         --it;         b = it->second;         it = e.find(make_pair(a, b));         if (it != e.end()) e.erase(it);         e.insert(make_pair(a, p[i].k));         e.insert(make_pair(p[i].k, b));         s.insert(make_pair(p[i].h, p[i].k));       }     }     for (it = e.begin(); it != e.end(); it++)       tran[it->first].push_back(it->second);     dp[0] = (1ll << 50);     for (int i = 0; i < n + 2; i++) {       int now = q[i].k;       for (int j = 0; j < tran[now].size(); j++) {         int tag = tran[now][j];         dp[tag] = max(             dp[tag], min(dp[now], min((long long)r[now], (long long)r[tag]) -                                       max((long long)l[now], (long long)l[tag])));       }     }     printf( %I64d n , dp[n + 1]);     return 0;   }   