Competitions

# Graph representation

# Number of hanging vertices 2

Given a simple undirected unweighted graph. Count the number of hanging vertices in it. The vertex is hanging, if its degree is **1**.

#### Input

The first line contains two numbers **n** and **m** (**1** ≤ **n**, **m** ≤ **1000**) - the number of vertices and the number of edges. Next **m** lines contain a list of edges.

#### Output

Print the number of hanging vertices in a graph.

Input example #1

2 1 1 2

Output example #1

2

Input example #2

3 3 1 2 1 3 2 3

Output example #2

0