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
chinhchamhoc:
20191129 04:22:32
could someone tells me how to solve using DSU pls 

hduoc2003:
20190928 18:08:29
Weak test cases.


prmondal:
20190701 17:39:21
Last edit: 20190705 08:55:25 

ab_biswas09:
20190316 17:21:41
coordinate compression => 0.04 sec 

tanmayak99:
20190113 15:05:14
Did it with (Lazy+Segtree) . How to do it with Coordinate compression ? 

anshumanc007:
20181214 11:36:03
solved with lazy prop! how to do with DSU?


phoemur:
20181124 23:13:14
With coordinate compression even a naive O(n*m) gets AC here


lapmid:
20181026 16:54:47
AC using Lazy , Anyone Please explain this using DSU 

dlp_302:
20181008 16:21:21
dsu


kaiser17:
20180711 21:04:20
too easy 
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 