#include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ull = unsigned long long;

#define IOS ios::sync_with_stdio(0);cin.tie(0);
#define endl "\n"
#define yes cout<<"Yes"<<endl;
#define no cout<<"No"<<endl;
#define irep(i, l, r) for(int i = l; i <= r; ++ i)
void solve() {
	int n, m;
	cin >> n >> m;
	//cerr << n <<' '<< m <<endl;
	vector<int>fa(n);

	auto find = [&](auto self, int x) -> int{
		if(fa[x] == x)return fa[x];
		fa[x] = self(self, fa[x]);
		return fa[x];
	};
	auto merge = [&](int u, int v) -> void{
		fa[find(find, u)] = find(find, v);
	};

	vector<int>ans;
	vector<vector<int>>t(n);
	vector<int>dis;
	vector<int>vis(n);
	vector<array<int,2>>e;
	auto dfs = [&](auto self,int ed, int x) -> void{
		vis[x] = 1;
		if(x == ed){
			ans = dis;
		}
		for(int eg : t[x]){
			auto [u, v] = e[eg];
			int y = u + v - x;
			if(vis[y])continue;
			dis.push_back(eg);
			self(self, ed, y);
			dis.pop_back();
		}
		vis[x] = 0;
	};
	irep(i, 0, n - 1)fa[i] = i;
	int flag = 0;
	irep(i, 0, m - 1){
		int u, v;
		cin >> u >> v;
		if(flag == 1){
			continue;
		}
		u -- ,v -- ;
		if(find(find, u) == find(find, v)){
			flag = 1;
			dfs(dfs, u, v);
			sort(ans.begin(), ans.end());
			for(int xx : ans){
				cout << xx + 1 << ' ';
			}
			cout << i + 1 << '\n';
			//return;
		}
		merge(u, v);
		e.push_back({u, v});
		t[u].emplace_back(i);
		t[v].emplace_back(i);
	}
	if(flag == 0)puts("-1");
	return;
}


int main() {
  //  IOS
    int t;
    cin >> t;
    while (t--)solve();
}