#include <iostream>
#include <vector>
#include <cstdio>
#include <algorithm>
#include <utility>
#include <cstring>
using namespace std;
typedef struct _node
{
int v, id, num;
_node():num(0) {};
}N;
const int MAX = 10005;
vector<N> vec[MAX];
int dfn[MAX], low[MAX], step, id;
int ans[MAX * 10], cnt;
void addEdge(int u, int v)
{
bool flag = false;
for(unsigned i = 0; i < vec[u].size(); i++)
{
if(vec[u][i].v == v)
{
flag = true;
vec[u][i].num++;
for(unsigned j = 0; j < vec[v].size(); j++)
{
if(vec[v][j].v == u)
{
vec[v][j].num++;
break;
}
}
id++;
break;
}
}
if(flag == false)
{
N tmp;
tmp.v = v, tmp.id = id++;
tmp.num = 1;
vec[u].push_back(tmp);
tmp.v = u;
vec[v].push_back(tmp);
}
}
void tarjan(int father, int n)
{
dfn[n] = low[n] = ++step;
for(unsigned i = 0; i < vec[n].size(); i++)
{
int son = vec[n][i].v;
if(dfn[son] == -1)
{
tarjan(n, son);
low[n] = min(low[n], low[son]);
}
else if(son != father)
low[n] = min(low[n], dfn[son]);
}
if(dfn[n] == low[n])
{
int son = n;
n = father;
for(unsigned k = 0; k < vec[n].size(); k++)
{
if(son == vec[n][k].v)
{
if(vec[n][k].num == 1)
{
ans[cnt++] = vec[n][k].id;
}
break;
}
}
}
}
void init()
{
id = 1;
step = cnt = 0;
for(int i = 0; i < MAX; i++)
{
vec[i].clear();
dfn[i] = low[i] = -1;
}
}
int main(void)
{
#ifndef ONLINE_JUDGE
//freopen("in.txt", "r", stdin);
#endif
int cas;
scanf("%d", &cas);
while(cas--)
{
init();
int n, m;
scanf("%d %d", &n, &m);
for(int i = 0; i < m; i++)
{
int u, v;
scanf("%d %d", &u, &v);
addEdge(u, v);
}
dfn[1] = low[1] = ++step;
tarjan(1, 1);
printf("%d\n", cnt);
if(cnt)
{
sort(ans, ans + cnt);
printf("%d", ans[0]);
for(int i = 1; i < cnt; i++)
{
printf(" %d", ans[i]);
}
printf("\n");
}
if(cas)
printf("\n");
}
return 0;
}