// MagicDark
#include <bits/stdc++.h>
#define mid ((l + r) >> 1)
#define lc num << 1
#define rc lc | 1
#define li lc, l, mid
#define ri rc, mid + 1, r
#define debug cerr << "\33[32m[" << __LINE__ << "]\33[m "
#define SZ(x) ((int) x.size() - 1)
#define all(x) x.begin(), x.end()
#define ms(x, y) memset(x, y, sizeof x)
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define DF(i, x, y) for (int i = (x); i >= (y); i--)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template <typename T> T& chkmax(T &x, T y) {return x = max(x, y);}
template <typename T> T& chkmin(T &x, T y) {return x = min(x, y);}
template <typename T> T& read(T &x) {
	x = 0; int f = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') f = - f;
	for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
	return x *= f;
}
const int N = 1e6 + 10, inf = 2e9;
int n, l[N], r[N], m;
vector <int> v[N];
vector <pair <int, int>> vv[N];
int ss[N], ans[N];
void zhk() {
	read(n);
	set <pair <int, int>> s;
	F(i, 1, n) {
		ans[i] = 0;
		read(l[i]), read(r[i]);
		F(_, 1, 3) {
			auto pos = s.lower_bound(make_pair(l[i], inf));
			int tl = l[i], tr = l[i];
			if (pos != s.begin()) {
				auto pp = prev(pos);
				if (pp -> second + 1 >= l[i]) {
					tl = pp -> first;
					tr = pp -> second + 1;
					s.erase(pp);
				}
			}
			if (pos != s.end() && pos -> first == tr + 1) {
				tr = pos -> second;
				s.erase(pos);
			}
			s.emplace(tl, tr);
		}
	}
	vector <int> w;
	for (auto [l, r]: s)
		F(i, l, r) w.push_back(i);
	m = w.size();
	set <int> g;
	F(i, 1, m + 5) g.insert(i), v[i].clear(), vv[i].clear();
	F(i, 0, m + 1) ss[i] = 0;
	F(i, 1, n) {
		l[i] = lower_bound(all(w), l[i]) - w.begin() + 1;
		r[i] = upper_bound(all(w), r[i]) - w.begin();
		v[r[i]].push_back(l[i]);
		vv[l[i]].emplace_back(r[i], i);
	}
	F(i, 1, m) {
		for (int j: v[i]) {
			auto it = g.upper_bound(j);
			F(_, 1, 2) {
				if (* it == i + 3) {
					puts("-1");
					return;
				}
				it = g.erase(it);
			}
		}
		auto pos = prev(g.lower_bound(i + 3));
		int w = * pos;
		if (w <= i) {
			ss[w]++, ss[i + 2]--;
		}
	}
	priority_queue <pair <int, int>, vector <pair <int, int>>, greater <pair <int, int>>> q;
	vector <int> gg;
	F(i, 1, m) {
		if (i > 1) ss[i] += ss[i - 2];
		if (ss[i]) gg.push_back(i);
	}
	if (gg.empty()) {
		for (int i = 1; i <= m; i += 2) ss[i] = 1;
	} else {
		vector <int> stk;
		int mx = 0;
		bool gt;
		auto upd = [&] (int x) {
			bool flag = true;
			for (int j: v[x]) {
				auto it = g.lower_bound(j);
				if (it == g.end()) {
					gt = false;
					return false;
				}
				int vw = * it;
				chkmax(mx, vw);
				stk.push_back(vw);
				g.erase(it);
				if (vw > x) flag = false;
			}
			return flag;
		};
		g.clear();
		for (int i = gg.front() - 2; i >= 1; i -= 2) ss[i] = 1, g.insert(i);
		g.insert(gg.front());
		F(i, 1, gg.front() - 1) {
			if (!upd(i)) {
				puts("-1");
				return;
			}
		}
		F(i, 0, SZ(gg) - 1) {
			g.insert(gg[i + 1]);
			if (!upd(gg[i])) {
				puts("-1");
				return;
			}
			bool flag = true;
			if ((gg[i + 1] - gg[i] - 1) & 1) {
				for (int j = gg[i] + 2; j + 1 < gg[i + 1]; j += 2) {
					ss[j] = 1;
					g.insert(j);
				}
			} else {
				for (int j = gg[i] + 3; j + 1 < gg[i + 1]; j += 2) {
					ss[j] = 1;
					g.insert(j);
				}
				int pos = stk.size();
				int lst = 0;
				gt = true;
				flag = false;
				mx = 0;
				F(j, gg[i] + 1, gg[i + 1] - 1) {
					upd(j);
					if (!gt) {
						puts("-1");
						return;
					}
					if (mx > j) {
						if ((j - gg[i]) & 1 || j == gg[i + 1] - 1) {
							puts("-1");
							return;
						}
						lst = j;
					}
				}
				if (lst) {
					flag = true;
					while (stk.size() > pos) {
						int x = stk.back(); stk.pop_back();
						g.insert(x);
					}
					for (int k = gg[i] + 3; k <= lst + 1; k += 2) {
						ss[k] = 0;
						g.erase(k);
					}
					for (int k = gg[i] + 2; k <= lst; k += 2) {
						ss[k] = 1;
						g.insert(k);
					}
				}
			}
			if (flag) {
				F(j, gg[i] + 1, gg[i + 1] - 1) {
					if (!upd(j)) {
						puts("-1");
						return;
					}
				}
			}
		}
		for (int i = gg.back() + 2; i <= m; i += 2) ss[i] = 1, g.insert(i);
	}
	F(i, 1, m - 1)
		if (ss[i] && ss[i + 1]) {
			puts("-1");
			return;
		}
	F(i, 1, m) {
		for (auto t: vv[i]) q.push(t);
		if (ss[i]) {
			if (q.size()) {
				auto [a, b] = q.top(); q.pop();
				if (a < i) {
					puts("-1");
					return;
				}
				ans[b] = i;
			}
		}
	}
	F(i, 1, n) cout << w[ans[i] - 1] << ' '; cout << '\n';
}
signed main() {
	int _ = 1;
	cin >> _;
	while (_--) zhk();
	return 0;
}
/* why?
*/