#include <bits/stdc++.h>
using namespace std;

#ifdef CKISEKI
#define safe cerr << __PRETTY_FUNCTION__ << " line " << __LINE__ << " safe\n"
#define debug(a...) debug_(#a, a)
#define orange(a...) orange_(#a, a)
template <typename ...T>
void debug_(const char *s, T ...a) {
    cerr << "\e[1;32m(" << s << ") = (";
    int cnt = sizeof...(T);
    (..., (cerr << a << (--cnt ? ", " : ")\e[0m\n")));
}
template <typename I>
void orange_(const char * s, I L, I R) {
    cerr << "\e[1;32m[" << s << "] = [ ";
    for (int f = 0; L != R; ++L)
        cerr << (f++ ? ", " : "") << *L;
    cerr << " ]\e[0m\n";
}
#else
#define safe ((void)0)
#define debug(...) safe
#define orange(...) safe
#endif

void solve() {
    int N, M;
    cin >> N >> M;
    vector<pair<int,int>> seg;
    for (int i = 0; i < M * 2; i++) {
        int l, r;
        cin >> l >> r;

        // l = rand() % N + 1;
        // r = rand() % N + 1;
        // if (l > r) swap(l, r);

        seg.emplace_back(r - l + 1, -r);
    }

    sort(seg.begin(), seg.end(), greater<>());
    auto [k, pos] = seg[M - 1];

    if (k == 1) {
        cout << -1 << '\n';
        return;
    }

    pos = -pos;

    // vector<int> A(N + 1);
    for (int i = 1; i <= N; i++) {
        int a;
        if (i <= pos) {
            a = (pos - i) % (k - 1) + 1;
        } else {
            a = k - (i - pos - 1) % k;
        }

        cout << a << (i==N ? '\n' : ' ');
        // A[i] = a;
    }

//    int c = 0;
//    for (auto [len, _r]: seg) {
//        int r = -_r;
//        int l = r - len + 1;
//        debug(l, r);
//        int sz = set<int>(A.begin() + l, A.begin() + r + 1).size();
//        if (sz == len)
//            ++c;
//    }
//    assert (c == M);


}

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    int T;
    cin >> T;
    while (T--)
        solve();
    return 0;
}