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Happy Vertices

Problem

Editorial

Analytics

You are given a graph with *N* vertices and *M* edges. Master parent is the vertex which has no parent but may have 0 or more children. In any connected component of the graph,vertex with the lowest value in that component serves as the master parent.

A vertex is called happy if it has more children than its parent. Count the number of happy vertices in the given graph.The graph has no cycles or self loops.

**Input Format**:

First line consists of two space separated integers denoting *N* and *M* and the following *M* lines consist of two space separated integers *X* and *Y* denoting there is an edge between vertices *X* and *Y*.

**Output Format**:

Print the number of happy vertices in the graph.

**Constraints**:

\( 1 \le N \le 100000\)

\( 0 \le M \le N-1 \)

\( 1 \le X, Y \le N \)

Explanation

In this graph, we have vertices 1,2,3 and 4. Since 1 is the lowest among these, so it becomes the master vertex. Now, 1 has only 1 child while 2 has two children.So, 2 is a happy vertex. There are no more happy vertices in the graph.

Time Limit:
1.0 sec(s)
for each input file.

Memory Limit:
256 MB

Source Limit:
1024 KB

Marking Scheme:
Marks are awarded when all the testcases pass.

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Initializing Code Editor...

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