#pragma GCC optimize "O3"
#include<bits/stdc++.h>
using namespace std;
using LL=long long;
#define FOR(i,l,r) for(int i=(l);i<=(r);++i)
#define REP(i,n) FOR(i,0,(n)-1)
#define ssize(x) int(x.size())
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto&operator<<(auto&o,tuple<auto,auto,auto>p){return o<<"("<<get<0>(p)<<", "<<get<1>(p)<<", "<<get<2>(p)<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(x...) cerr<<"["#x"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(x)
#else
#define debug(...) {}
#endif

int main() {
	cin.tie(0)->sync_with_stdio(0);
	int tests;
	cin >> tests;
	REP (test, tests) {
		int n;
		cin >> n;
		map<LL, vector<int>> mp;
		REP (i, n) {
			int x, y;
			cin >> x >> y;
			mp[x + y].emplace_back(y);
		}
		mp[LL(3e9)] = vector<int>();
		set<tuple<int, int, int>> t;
		t.emplace(0, 0, 1);
		LL last = 0;
		bool broken = false;
		for (auto [tm, v] : mp) {
			if (broken)
				break;
			debug(t);
			while (last < tm) {
				if (t.empty()) {
					last = tm;
					break;
				}
				if (broken)
					break;
				++last;
				map<int, int> g;
				for (auto [l, r, w] : t) {
					g[l] += w - 1;
					g[l + 1] += w - 1;
					g[r + 1] -= w - 1;
					g[r + 2] -= w - 1;
				}
				int prv = 0, cur = 0;
				set<tuple<int, int, int>> s;
				for (auto [y, w] : g) {
					if (!w)
						continue;
					if (cur) {
						s.emplace(prv, y - 1, cur);
						if (cur > 3) {
							broken = true;
						}
					}
					cur += w;
					prv = y;
				}
				assert(cur == 0);
				t = s;
				debug(last, t);
				int last_r = -2;
				int last_w = 0;
				for (auto [l, r, w] : t) {
					if (last_r + 1 == l) {
						if ((w == 2 && last_w == 3) || (last_w == 2 && w == 3)) {
							broken = true;
						}
					}
					last_r = r;
					last_w = w;
				}
				if (broken)
					break;
			}
			debug(v);
			for (auto y : v) {
				debug(y);
				auto ptr = t.lower_bound(tuple(y + 1, 0, 0));
				if (ptr == t.begin())
					continue;
				--ptr;
				auto [l, r, w] = *ptr;
				debug(l, r, w);
				if (l <= y && y <= r) {
					assert(w);
					if (w >= 3) {
						broken = true;
						break;
					}
					t.erase(ptr);
					if (l < y)
						t.emplace(tuple(l, y - 1, w));
					t.emplace(tuple(y, y, w + 1));
					if (y < r)
						t.emplace(tuple(y + 1, r, w));
				}
				debug(t);
				if (broken)
					break;
			}
			debug("after", t);
		}
		if (broken) {
			cout << "NO\n";
		}
		else {
			cout << "YES\n";
		}
	}
}
/*
[t]: {(0, 0, 1)}; 
[v]: {0}; 
[y]: 0; 
[l, r, w]: 0; 0; 1; 
[t]: {(0, 0, 2)}; 
["after", t]: after; {(0, 0, 2)}; 
[t]: {(0, 0, 2)}; 
[last, t]: 1; {(0, 1, 1)}; 
[v]: {1,0}; 
[y]: 1; 
[l, r, w]: 0; 1; 1; 
[t]: {(0, 0, 1),(1, 1, 2)}; 
[y]: 0; 
[l, r, w]: 0; 0; 1; 
[t]: {(0, 0, 2),(1, 1, 2)}; 
["after", t]: after; {(0, 0, 2),(1, 1, 2)}; 
[t]: {(0, 0, 2),(1, 1, 2)}; 
[last, t]: 2; {(0, 0, 1),(1, 1, 2),(2, 2, 1)}; 
[v]: {2,1}; 
[y]: 2; 
[l, r, w]: 2; 2; 1; 
[t]: {(0, 0, 1),(1, 1, 2),(2, 2, 2)}; 
[y]: 1; 
[l, r, w]: 1; 1; 2; 
[t]: {(0, 0, 1),(1, 1, 3),(2, 2, 2)}; 
["after", t]: after; {(0, 0, 1),(1, 1, 3),(2, 2, 2)}; 
[t]: {(0, 0, 1),(1, 1, 3),(2, 2, 2)}; 
[last, t]: 3; {(1, 1, 2),(2, 2, 3),(3, 3, 1)}; 
[v]: {0}; 
[y]: 0; 
["after", t]: after; {(1, 1, 2),(2, 2, 3),(3, 3, 1)}; 
[t]: {(1, 1, 2),(2, 2, 3),(3, 3, 1)}; 
[last, t]: 4; {(1, 1, 1),(2, 2, 3),(3, 3, 2)}; 
[last, t]: 5; {(2, 2, 2),(3, 3, 3),(4, 4, 1)}; 
[last, t]: 6; {(2, 2, 1),(3, 3, 3),(4, 4, 2)}; 
[last, t]: 7; {(3, 3, 2),(4, 4, 3),(5, 5, 1)}; 
[last, t]: 8; {(3, 3, 1),(4, 4, 3),(5, 5, 2)}; 
[last, t]: 9; {(4, 4, 2),(5, 5, 3),(6, 6, 1)}; 
[last, t]: 10; {(4, 4, 1),(5, 5, 3),(6, 6, 2)}; 
[last, t]: 11; {(5, 5, 2),(6, 6, 3),(7, 7, 1)}; 
[last, t]: 12; {(5, 5, 1),(6, 6, 3),(7, 7, 2)}; 
[last, t]: 13; {(6, 6, 2),(7, 7, 3),(8, 8, 1)}; 
[last, t]: 14; {(6, 6, 1),(7, 7, 3),(8, 8, 2)}; 
[last, t]: 15; {(7, 7, 2),(8, 8, 3),(9, 9, 1)}; 
[last, t]: 16; {(7, 7, 1),(8, 8, 3),(9, 9, 2)}; 
[last, t]: 17; {(8, 8, 2),(9, 9, 3),(10, 10, 1)}; 
[last, t]: 18; {(8, 8, 1),(9, 9, 3),(10, 10, 2)}; 
[last, t]: 19; {(9, 9, 2),(10, 10, 3),(11, 11, 1)}; 
[last, t]: 20; {(9, 9, 1),(10, 10, 3),(11, 11, 2)}; 
[last, t]: 21; {(10, 10, 2),(11, 11, 3),(12, 12, 1)}; 
[last, t]: 22; {(10, 10, 1),(11, 11, 3),(12, 12, 2)}; 
[last, t]: 23; {(11, 11, 2),(12, 12, 3),(13, 13, 1)}; 
[last, t]: 24; {(11, 11, 1),(12, 12, 3),(13, 13, 2)}; 
[last, t]: 25; {(12, 12, 2),(13, 13, 3),(14, 14, 1)}
*/