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.
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 $$Y$$.
Print the number of happy vertices in the graph.
$$ 1 \le N \le 100000$$
$$ 0 \le M \le N-1 $$
$$ 1 \le X, Y \le N $$
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.