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Problem of the day

There are ‘N’ servers numbered from ‘1’ to ‘N’ connected by undirected server-to-server connections forming a network.

You are given a matrix ‘EDGES’ storing the information about the connections, where each row, ‘EDGES[i]’ contains two integers ‘U’ and ‘V’, which implies that there is an undirected server-to-server connection between ‘U’ and ‘V’.

Any server can reach other servers directly or indirectly through the network.

A **critical** connection is a connection that, if removed, will make some servers unable to reach some other server.

Return all **critical** connections in the network in any order. If there are no **critical** connections return empty matrix.

```
For the given graph
```

```
If we remove the connection between ‘2’ and ‘4’. Then ‘4’ will not be reachable from any other server.
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Detailed explanation

```
The first line contains an integer 'T' which denotes the number of test cases.
The first line of each test case contains two integers ‘N’ and ‘M’, denoting the number of servers and number of connections respectively.
The following ‘M’ lines contain two integers ‘U’ and ‘V’ denoting there is an undirected server-to-server connection between server ‘U’ and server ‘V’.
```

```
For each test case, print all the critical connections in any order on separate lines.
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```
You don't need to print anything, it has already been taken care of. Just implement the given function.
```

```
1 ≤ T ≤ 10
2 ≤ N ≤ 100
N - 1 ≤ M ≤ 100
1 ≤ U, V ≤ N
Time limit: 1 sec
```

```
2
4 4
1 2
1 3
2 3
2 4
3 2
1 2
2 3
```

```
2 4
1 2
2 3
```

```
In test case 1, the graph is shown below.
```

```
If we remove the connection between ‘2’ and ‘4’. Then ‘4’ will not be reachable from any other server.
In test case 2, the graph is shown below.
```

```
If we remove the connection between ‘3’ and ‘2’. Then ‘3’ will not be reachable from any other server. Similarly, if we remove the connection between ‘1’ and ‘2’. Then ‘1’ will not be reachable from any other server.
```

```
2
2 1
1 2
4 4
1 2
1 3
3 4
2 4
```

```
1 2
```

```
In test case 1, the graph is shown below.
```

```
If we remove the connection between ‘1’ and ‘2’. Then ‘1’ will not be reachable from any other server.
In test case 2, the graph is shown below.
```

```
No matter which connection we remove it is not possible to make some servers unable to reach some other server.
```