{"raw_statement":[{"iden":"problem statement","content":"You are given an undirected connected graph with $N$ vertices and $M$ edges that does not contain self-loops and double edges.  \nThe $i$\\-th edge $(1 \\leq i \\leq M)$ connects Vertex $a_i$ and Vertex $b_i$.\nAn edge whose removal disconnects the graph is called a _bridge_.  \nFind the number of the edges that are bridges among the $M$ edges."},{"iden":"notes","content":"*   A _self-loop_ is an edge $i$ such that $a_i=b_i$ $(1 \\leq i \\leq M)$.\n*   _Double edges_ are a pair of edges $i,j$ such that $a_i=a_j$ and $b_i=b_j$ $(1 \\leq i<j \\leq M)$.\n*   An undirected graph is said to be _connected_ when there exists a path between every pair of vertices."},{"iden":"constraints","content":"*   $2 \\leq N \\leq 50$\n*   $N-1 \\leq M \\leq min(N(N−1)⁄2,50)$\n*   $1 \\leq a_i<b_i \\leq N$\n*   The given graph does not contain self-loops and double edges.\n*   The given graph is connected."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$ $M$  \n$a_1$ $b_1$  \n$a_2$ $b_2$\n$:$  \n$a_M$ $b_M$"},{"iden":"sample input 1","content":"7 7\n1 3\n2 7\n3 4\n4 5\n4 6\n5 6\n6 7"},{"iden":"sample output 1","content":"4\n\nThe figure below shows the given graph:\n\n![image](https://img.atcoder.jp/abc075/570677a9809fd7a5b63bff11e5d9bf79.png)\n\nThe edges shown in red are bridges. There are four of them."},{"iden":"sample input 2","content":"3 3\n1 2\n1 3\n2 3"},{"iden":"sample output 2","content":"0\n\nIt is possible that there is no bridge."},{"iden":"sample input 3","content":"6 5\n1 2\n2 3\n3 4\n4 5\n5 6"},{"iden":"sample output 3","content":"5\n\nIt is possible that every edge is a bridge."}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}