POSTERS  Election Posters
A parliamentary election was being held in Byteland. Its enterprising and orderly citizens decided to limit the entire election campaign to a single dedicated wall, so as not to ruin the panorama with countless posters and billboards. Every politician was allowed to hang exactly one poster on the wall. All posters extend from top to bottom, but are hung at different points of the wall, and may be of different width. The wall is divided horizontally into sections, and a poster completely occupies two or more adjacent sections.
With time, some of the posters were covered (partially or completely) by those of other politicians. Knowing the location of all the posters and the order in which they were hung, determine how many posters have at least one visible section in the end.
Input
The input begins with the integer t, the number of test cases. Then t test cases follow.
Each test case begins with a line containing integer n  the number of posters (1 <= n <= 40000). Then n lines follow, the ith (1 <= i <= n) containing exactly two integers l_{i} r_{i}, denoting the numbers of the leftmost and rightmost sections covered by the ith poster (1 <= l_{i} < r_{i} <= 10^{7}). The input order corresponds to the order of hanging posters.
Output
For each test case output a line containing one integerĀ  the number of posters with visible sections.
Example
Sample input: 1 5 1 4 2 6 8 10 3 4 7 10 Sample output: 4
An illustration of the sample input is given below.
hide comments
sharif ullah:
20171115 10:53:16
1


prayassahni:
20161029 18:43:47
can't find a test case wrong but getting WA(lazy propgation+segment tree) 

sieunhanbom04:
20160817 19:50:23
weak test cases I suppose 

fork_my_code:
20160731 08:15:16
just go through image and write code blindly using set 

VISHAL ASHANK:
20160727 03:52:18
nice problem.. no need of coordinate compression.. just be lazy 

m_elbrbry:
20160621 12:30:38
@Jannatul Ferdows Jenny


j1k7_7(JaskamalKainth):
20160614 11:11:07
Basic Segment tree with Lazy Prop , Coord Compression.


minhthai:
20160210 16:25:12
if u use sweep, be careful with the coordinate format 

saurabh anand:
20160101 18:30:25
segment tree + lazy propagation takes < 0.5 s 

azizul hakim:
20151221 08:42:32
Use coordinate compression. that saves both time, and also saves from overflow while summing... _ got so many wa. 
Added by:  adrian 
Date:  20040719 
Time limit:  7s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All 
Resource:  VI Polish Collegiate Team Programming Contest (AMPPZ), 2001 