9208: ABC288 —— C - Don’t be cycle
[Creator : ]
Description
### Problem Statement
You are given a simple undirected graph with $N$ vertices and $M$ edges. The vertices are numbered $1$ to $N$, and the $i$\-th edge connects vertex $A_i$ and vertex $B_i$. Let us delete zero or more edges to remove cycles from the graph. Find the minimum number of edges that must be deleted for this purpose.
What is a simple undirected graph? A simple undirected graph is a graph without self-loops or multi-edges whose edges have no direction.
What is a cycle? A cycle in a simple undirected graph is a sequence of vertices $(v_0, v_1, \ldots, v_{n-1})$ of length at least $3$ satisfying $v_i \neq v_j$ if $i \neq j$ such that for each $0 \leq i < n$, there is an edge between $v_i$ and $v_{i+1 \bmod n}$.
You are given a simple undirected graph with $N$ vertices and $M$ edges. The vertices are numbered $1$ to $N$, and the $i$\-th edge connects vertex $A_i$ and vertex $B_i$. Let us delete zero or more edges to remove cycles from the graph. Find the minimum number of edges that must be deleted for this purpose.
What is a simple undirected graph? A simple undirected graph is a graph without self-loops or multi-edges whose edges have no direction.
What is a cycle? A cycle in a simple undirected graph is a sequence of vertices $(v_0, v_1, \ldots, v_{n-1})$ of length at least $3$ satisfying $v_i \neq v_j$ if $i \neq j$ such that for each $0 \leq i < n$, there is an edge between $v_i$ and $v_{i+1 \bmod n}$.
Input
### Input
The input is given from Standard Input in the following format:
```
$N$ $M$
$A_1$ $B_1$
$A_2$ $B_2$
$\vdots$
$A_M$ $B_M$
```
The input is given from Standard Input in the following format:
```
$N$ $M$
$A_1$ $B_1$
$A_2$ $B_2$
$\vdots$
$A_M$ $B_M$
```
Output
### Output
Print the answer.
Print the answer.
Constraints
### Constraints
- $1 \leq N \leq 2 \times 10^5$
- $0 \leq M \leq 2 \times 10^5$
- $1 \leq A_i, B_i \leq N$
- The given graph is simple.
- All values in the input are integers.
- $1 \leq N \leq 2 \times 10^5$
- $0 \leq M \leq 2 \times 10^5$
- $1 \leq A_i, B_i \leq N$
- The given graph is simple.
- All values in the input are integers.
Sample 1 Input
6 7
1 2
1 3
2 3
4 2
6 5
4 6
4 5
Sample 1 Output
2
One way to remove cycles from the graph is to delete the two edges between vertex 1 and vertex 2 and between vertex 4 and vertex 5.
There is no way to remove cycles from the graph by deleting one or fewer edges, so you should print 2.
There is no way to remove cycles from the graph by deleting one or fewer edges, so you should print 2.
Sample 2 Input
4 2
1 2
3 4
Sample 2 Output
0
Sample 3 Input
5 3
1 2
1 3
2 3
Sample 3 Output
1