#include <bits/stdc++.h>
namespace my_std {
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename T>
inline T rnd(T l, T r) {
  return uniform_int_distribution<T>(l, r)(rng);
}
template <typename T>
inline bool chkmax(T& x, T y) {
  return x < y ? x = y, 1 : 0;
}
template <typename T>
inline bool chkmin(T& x, T y) {
  return x > y ? x = y, 1 : 0;
}
template <typename T>
inline void read(T& t) {
  t = 0;
  char f = 0, ch = getchar();
  double d = 0.1;
  while (ch > '9' || ch < '0') f |= (ch == '-'), ch = getchar();
  while (ch <= '9' && ch >= '0') t = t * 10 + ch - 48, ch = getchar();
  if (ch == '.') {
    ch = getchar();
    while (ch <= '9' && ch >= '0') t += d * (ch ^ 48), d *= 0.1, ch = getchar();
  }
  t = (f ? -t : t);
}
template <typename T, typename... Args>
inline void read(T& t, Args&... args) {
  read(t);
  read(args...);
}
char __sr[1 << 21], __z[20];
int __C = -1, __zz = 0;
inline void Ot() { fwrite(__sr, 1, __C + 1, stdout), __C = -1; }
inline void print(int x) {
  if (__C > 1 << 20) Ot();
  if (x < 0) __sr[++__C] = '-', x = -x;
  while (__z[++__zz] = x % 10 + 48, x /= 10)
    ;
  while (__sr[++__C] = __z[__zz], --__zz)
    ;
  __sr[++__C] = '\n';
}
void file() {}
inline void chktime() {}
long long ksm(long long x, int y) {
  long long ret = 1;
  for (; y; y >>= 1, x = x * x)
    if (y & 1) ret = ret * x;
  return ret;
}
}  // namespace my_std
using namespace my_std;
int n, L;
double l[402020], v[402020];
int m;
double rs[402020];
priority_queue<pair<double, int> > q;
int main() {
  file();
  read(n, L);
  auto add = [&](int x, int y, double vv) {
    if (x != y) l[++m] = y - x, v[m] = vv;
  };
  int x, y;
  double vv;
  read(x, y, vv);
  add(0, x, 0);
  add(x, y, vv);
  for (int i = (2); i <= (n); i++)
    read(x), add(y, x, 0), read(y, vv), add(x, y, vv);
  add(y, L, 0);
  double ans = 0;
  for (int i = (1); i <= (m); i++) {
    double r = (v[i] < 1e-3 ? 1e9 : l[i] / v[i]), l = ::l[i] / (v[i] + 2);
    rs[i] = r - l;
    double t = ::l[i], k = v[i] + 1;
    t -= l * k;
    ans += l;
    q.push(make_pair(k, i));
    while (t) {
      pair<double, int> p = q.top();
      q.pop();
      int x = p.second;
      if (rs[x] * p.first < t) {
        t -= rs[x] * p.first;
        ans += rs[x];
        continue;
      }
      rs[x] -= t / p.first, ans += t / p.first;
      t = 0;
      q.push(p);
    }
  }
  printf("%.10lf\n", ans);
  return 0;
}
