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

using ll = long long;
using ld = long double;
using pii = pair<ll, ll>;
using vi = vector<ll>;
using vvi = vector<vi>;
#define rep(i, a, b) for(ll i = (a); i < (b); i++)
#define all(x) begin(x),end(x)
#define sz(x) (int)(x).size()

void solve() {
    ll n;
    cin >> n;
    set<ll> s;
    function<void(ll)> addto = [&] (ll x) {
        if (s.contains(x))
            s.erase(x), addto(x - 1);
        else
            s.insert(x);
    };
    rep(i,0,n) {
        ll c, d;
        cin >> c >> d;
        addto(c + d);
    }
    auto x = *begin(s);
    s.erase(begin(s));
    if (x < -1)
        return void(cout << "NO\n");
    else if (x > -1)
        return void(cout << "YES\n");
    if (empty(s))
        return void(cout << "YES\n");
    auto y = *begin(s);
    if (y == 0)
        return void(cout << "NO\n");
    else
        return void(cout << "YES\n");
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    ll t; cin >> t; while(t--)
        solve();
}