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sarwarIT SELISE Coding Challenge 2...
Limits 1s, 512 MB

There are N cities in the country AjobDesh and M one way roads connecting the cities.

There lives exactly one AjobPrani in each of the N cities.
Every AjobPrani must visit at least one other AjobPrani if there is a path to visit. If possible then he should also return to his home town.

Find how many AjobPrani are unable to return to his home town.


First line contains the number of test cases T(1≤ T ≤10).

For each test case:

First line consists of two integers denoting N(1≤ N ≤100000) and M(0≤ M ≤200000).

Next M lines consist of two integers A and B denoting there is a directed road from A to B (1≤ A,B ≤N).The graph can contain self loops.


For every test case, you need to print “Case T: ” (where T is the test case number) followed by the number of AjobPrani who can't return.


5 6
1 2
2 3
2 5
5 3
5 1
4 5
Case 1: 1

Route for each AjobPrani:
AjobPrani 1: 1->2->5->1
AjobPrani 2: 2->5->1->2
AjobPrani 3: no way to visit any other AjobPrani
AjobPrani 4: 4->5 [can not return to 4]
AjobPrani 5: 5->1->2->5
So, only AjobPrani 4 can not return to his home town.


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53% Solution Ratio
NirjhorEarliest, Aug '20
Hridoy3519Fastest, 0.1s
EdgedancerLightest, 8.7 MB
NirjhorShortest, 1115B
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