#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<int, vector<int>> mp;
		REP (i, n) {
			int x, y;
			cin >> x >> y;
			mp[x + y].emplace_back(y);
		}
		set<tuple<int, int, int>> t;
		t.emplace(0, 0, 1);
		int 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);
			}
			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";
		}
	}
}