#include<bits/stdc++.h>

#pragma GCC optimize ("Ofast")

using namespace std;

#define rep(i,a,b) for(ll i = a; i<b;i++)
#define sz(v) ll(v.size())
#define all(v) v.begin(),v.end()

typedef long long ll;
typedef long double ld;
typedef vector<ll> vl;
typedef pair<ll,ll> pll;

int main(){
    cin.tie(0);
    ios_base::sync_with_stdio(0);

    int t;
    cin >> t;
    while(t--) {
        int n;
        cin >> n;
        priority_queue<int> dists;
        for(int i = 0; i < n; i++) {
            int a, b;
            cin >> a >> b;
            dists.push(a+b);
        }
        vector<int> remaining;
        while(dists.size()) {
            int a = dists.top(); dists.pop();
            if(dists.size() && dists.top() == a) {
                dists.pop();
                dists.push(a-1);
            } else {
                remaining.push_back(a);
            }
        }
        if(remaining.size() >= 2 && remaining.back() == -1 && remaining[remaining.size()-2] == 0)
            cout << "NO\n";
        else 
            cout << "YES\n";
    }
}