#include <bits/stdc++.h>
using namespace std;
int g[55][55];

int main() {
  int N,M,a,b;
  int ans=0;
  cin>>N>>M;
  vector<int>c(N);
  for(int i=0;i<N;i++)c[i]=0;
  for(int i=0;i<N;i++)for(int j=0;j<N;j++)g[i][j]=0;
  for(int i=0;i<M;i++){
    cin>>a>>b;
    a--;b--;
    c[a]++;c[b]++;
    g[a][b]++;
    g[b][a]++;
  }
  for(int i=0;i<N;i++){
    if(c[i]==1){
      ans++;
      for(int j=0;j<N;j++){
        if(g[i][j]==1){
          c[i]--;
          c[j]--;
          g[i][j]--;
          g[j][i]--;
        }
        }
        i=-1;
      }
    }
    cout<<ans<<endl;
  }

### Prompt

Generate a Cpp solution to the following problem:

You are given an undirected connected graph with N vertices and M edges that does not contain self-loops and double edges.
The i-th edge (1 \leq i \leq M) connects Vertex a_i and Vertex b_i.

An edge whose removal disconnects the graph is called a bridge.
Find the number of the edges that are bridges among the M edges.

Constraints

* 2 \leq N \leq 50
* N-1 \leq M \leq min(N(N−1)⁄2,50)
* 1 \leq a_i<b_i \leq N
* The given graph does not contain self-loops and double edges.
* The given graph is connected.

Input

Input is given from Standard Input in the following format:


N M
a_1 b_1
a_2 b_2
:
a_M b_M


Output

Print the number of the edges that are bridges among the M edges.

Examples

Input

7 7
1 3
2 7
3 4
4 5
4 6
5 6
6 7


Output

4


Input

3 3
1 2
1 3
2 3


Output

0


Input

6 5
1 2
2 3
3 4
4 5
5 6


Output

5

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
int g[55][55];

int main() {
  int N,M,a,b;
  int ans=0;
  cin>>N>>M;
  vector<int>c(N);
  for(int i=0;i<N;i++)c[i]=0;
  for(int i=0;i<N;i++)for(int j=0;j<N;j++)g[i][j]=0;
  for(int i=0;i<M;i++){
    cin>>a>>b;
    a--;b--;
    c[a]++;c[b]++;
    g[a][b]++;
    g[b][a]++;
  }
  for(int i=0;i<N;i++){
    if(c[i]==1){
      ans++;
      for(int j=0;j<N;j++){
        if(g[i][j]==1){
          c[i]--;
          c[j]--;
          g[i][j]--;
          g[j][i]--;
        }
        }
        i=-1;
      }
    }
    cout<<ans<<endl;
  }

```