#include <bits/stdc++.h>

using namespace std;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);

	int T;
	cin >> T;
	struct interval_t {
		int l, r;
		interval_t(int l, int r) : l(l), r(r) {}
		auto operator <=>(interval_t &rhs) {
			return make_pair(r - l, l) <=> make_pair(rhs.r - rhs.l, rhs.l);
		}
	};
	while (T--) {
		int n, m;
		cin >> n >> m;
		vector<interval_t> vec(2 * m, interval_t(-1, -1));
		for (int i = 0; i < 2 * m; ++i) {
			cin >> vec[i].l >> vec[i].r;
			--vec[i].l, --vec[i].r;
		}
		sort(vec.begin(), vec.end());
		if (vec[m].l == vec[m].r) {
			cout << -1 << '\n';
			continue;
		}
		int d = vec[m].r - vec[m].l + 1;
		vector<int> a(n);
		for (int i = 0; i < d; ++i)
			a[i] = i + 1;
		for (int i = d; i < vec[m].r; ++i)
			a[i] = a[i - d];
		for (int i = vec[m].r; i < n; ++i)
			a[i] = a[i - d + 1];
		for (int i = 0; i < n; ++i) {
			cout << a[i] << " \n"[i + 1 == n];
		}
	}
}