# -*- coding:utf8 -*-
# Given a link stream on stdin, a value of delta and the last timestamp of the stream, outputs the delta-density for each link.
# Date : December 2013
# Author : jvd

# Notes to self :
#   t_init is 0 (datafile needs to start at 0 too)

import sys
import pdb
import math

links = set()
delta = float(sys.argv[1])

links_dict = {}
t_init = 0
init_set = 0
tspan = float(sys.argv[2])
nodes = set()


def update_density(delta, t, link):
	""" Updates the value of delta density with information from the latest apparition
		
		@param delta : float The fixed value for delta
		@param t : float The timestamp of the latest link in stream
		@param link : tuple The latest two nodes (u,v) in the stream
	"""
	d = 0
	num = 0
	if links_dict[link][2] == 1:
	# The link appears for the first time
		d = max((t - t_init)-delta, 0)
	else:
	# The link appears, but it is not the first time
		intercontact_t = float(t) - float(links_dict[link][0])
		d = max(intercontact_t - delta, 0)

	# Update link info
	links_dict[link][2] += 1
	links_dict[link][1] += d
	links_dict[link][0] = t

for line in sys.stdin:
	# Get info from line
	contents = line.split(" ")
	t = int(contents[0].strip())
	u = int(contents[1].strip())
	v = int(contents[2].strip())

	# Add info to data structure
	nodes.add(u)
	nodes.add(v)
	link = frozenset([u,v])
	links.add(link)

	# Append ts, density (0), number of links apparitions
	if links_dict.get(link) is None:
		# 0 : intercontact sequence
		# 1 : Current value of deltadensity
		# 2 : Number of occurrences
		links_dict[link] = []
		links_dict[link].append(t_init)
		links_dict[link].append(0)
		links_dict[link].append(1)

	update_density(delta, t, link)

sys.stdout.write("%d\n" % len(nodes))
for link in links_dict:
	# Update with last term of sum
	if tspan - links_dict[link][0]	!= 0:
		links_dict[link][1] += max((tspan - float(links_dict[link][0]) - delta),0)
	
	# Print nodes ids if command-line arg has been stated
	if len(sys.argv) == 4 and sys.argv[3] == "--print-nodes":
		sys.stdout.write("%d %d" % (list(link)[0], list(link)[1]))

	# Print values of delta densities for each pair of nodes
	if links_dict[link][1] != 0:
		sys.stdout.write("%10f\n" % (1 - (links_dict[link][1]/(tspan - delta))))
	else:
	 	sys.stdout.write("%10f\n" % (1))