Preparing NOJ

*N* (1 ≤ *N* ≤ 100) cows, conveniently numbered 1..*N*, are participating in a programming contest. As we all know, some cows code better than others. Each cow has a certain constant skill rating that is unique among the competitors.

The contest is conducted in several head-to-head rounds, each between two cows. If cow *A* has a greater skill level than cow *B* (1 ≤ *A* ≤ *N*; 1 ≤ *B* ≤ *N*; *A* ≠ *B*), then cow *A* will always beat cow *B*.

Farmer John is trying to rank the cows by skill level. Given a list the results of *M* (1 ≤ *M* ≤ 4,500) two-cow rounds, determine the number of cows whose ranks can be precisely determined from the results. It is guaranteed that the results of the rounds will not be contradictory.

* Line 1: Two space-separated integers: *N* and *M*

* Lines 2..*M*+1: Each line contains two space-separated integers that describe the competitors and results (the first integer, *A*, is the winner) of a single round of competition: *A* and *B*

* Line 1: A single integer representing the number of cows whose ranks can be determined

5 5 4 3 4 2 3 2 1 2 2 5

2

Info

Provider POJ

Origin USACO 2008 January Silver

Code POJ3660

Tags

Submitted 0

Passed 0

AC Rate 0%

Date 03/06/2019 16:27:50

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