#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <vector>#include <map>using namespace std;const int V = 11111;vector<int> vec[V];vector<int> ans;map<int,int> tab;int dfn[V],low[V];int n,m;int hash(int s,int e){ if(s <= e){ return s*10000 + e; }else{ return e*10000 + s; }}void init(int n){ for(int i = 0 ; i <= n ; i ++){ vec[i].clear(); } ans.clear(); tab.clear(); memset(dfn,0,sizeof(dfn)); memset(low,0,sizeof(low));}void dfs(int cur,int fa,int dept){ dfn[cur] = low[cur] = dept; for(int i = 0 ; i < vec[cur].size() ; i++){ int tmp = vec[cur][i]; if(dfn[tmp] != 0 ){ if(tmp != fa){ if(dfn[tmp] < low[cur]) low[cur] = dfn[tmp]; } }else{ dfs(tmp,cur,dept+1); if(low[tmp] < low[cur]) low[cur] = low[tmp]; if(low[tmp] > dfn[cur]) { int temp = tab[hash(tmp,cur)]; if(temp != -1) ans.push_back(temp); } } }}void add(int s,int e,int p){ vec[s].push_back(e); vec[e].push_back(s); int tmp = hash(s,e); if(tab.count(tmp) == 0){ tab[tmp] = p; }else{ tab[tmp] = -1; }}int main(){ int T; scanf("%d",&T); for(int cas = 0 ; cas < T ; cas++){ if(cas != 0) puts(""); scanf("%d%d",&n,&m); init(n); int s,e; for(int i = 0 ; i < m ; i ++){ scanf("%d%d",&s,&e); add(s,e,i+1); } dfs(1,-1,1); sort(ans.begin(),ans.end()); printf("%dn",ans.size()); for(int i = 0 ; i < ans.size() ; i ++){ if(i == ans.size() - 1) printf("%dn",ans[i]); else printf("%d ",ans[i]); } } return 0;}
