#include <bits/stdc++.h>
#define int long long
using namespace std;
typedef long long ll;
#define pii pair<int, int>
#define fs first
#define sc second
#define pb push_back
#define mp make_pair

const int N = 105;
const int INF = 2e9 + 5;

struct edge {
    int u, v, p;
    edge *rev;
    edge(){}
    edge(int u, int v, int p, edge* rev = nullptr) {
        this->u = u;
        this->v = v;
        this->p = p;
        this->rev = rev;
    }
};

vector<edge*> g[N];

edge* ed[N * N];

int dist[N], cnt[N], n, m;
vector<bool> vis(N);

queue<int> q;

bool bfs(int v, int u) {
    fill(vis.begin(), vis.end(), false);
    q.push(v);
    vis[v] = true;
    dist[v] = 0;
    while(!q.empty()) {
        int v = q.front();
        q.pop();
        for (int i = 0; i < g[v].size(); i++) {
            int to = g[v][i]->v;
            if (vis[to] || g[v][i]->p == 0)
                continue;
            vis[to] = true;
            dist[to] = dist[v] + 1;
            q.push(to);
        }
    }
    return vis[u];
}

bool dfs(int v, int fn, int flow) {
    if (v == fn)
        return true;
    for (int i = cnt[v]; i < g[v].size(); i++, cnt[v]++) {
        if (g[v][i]->p == 0 || dist[g[v][i]->v] != dist[v] + 1)
            continue;
        if (dfs(g[v][i]->v, fn, 1)) {
            g[v][i]->p = 0;
            g[v][i]->rev->p = 1;
            return true;
        }
    }
    return false;
}

inline int getFlow(int u, int v) {
    int res = 0;
    while(bfs(u, v)) {
        for (int i = 0; i < n; i++)
            cnt[i] = 0;
        while(dfs(u, v, 1))
            res++;
    }

    for (int i = 0; i < m; i++) {
        if (ed[i]->p == 0 && ed[i]->rev->p == 1) {
            ed[i]->p = 1;
            ed[i]->rev->p = 0;
        }
    }
    return res;
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int tests;
    cin >> tests;
    while(tests--) {
        cin >> n >> m;
        for (int i = 0; i < n; i++)
            g[i].clear();
        for (int i = 0; i < m; i++) {
            int u, v;
            cin >> u >> v;
            u--, v--;
            g[u].pb(new edge(u, v, 1));
            g[v].pb(new edge(v, u, 0, g[u].back()));
            g[u].back()->rev = g[v].back();
            ed[i] = g[u].back();
        }
        pii good_pair;
        int ans = INF;

        for (int u = 0; u < n; u++) {
            for (int v = 0; v < n; v++) {
                if (u == v)
                    continue;
                int res = getFlow(u, v);
                if (res < ans) {
                    ans = res;
                    good_pair = mp(u, v);
                }
            }
        }
        cout << ans << endl;
        int u = good_pair.fs, v = good_pair.sc;

        for (int i = 0; i < m; i++) {
            ed[i]->p = 0;
            if (getFlow(u, v) == ans - 1) {
                ans--;
                cout << i + 1 << " ";
            }
            else
                ed[i]->p = 1;
        }
        cout << endl;
    }
}