#include <bits/stdc++.h>

using namespace std;

int n, spec, db[1100005];

void solve() {
    cin >> n;
    for (int i=1; i<=n; i++) {
        int x, y;
        cin >> x >> y;
        int sum=x+y-2;
        if (sum>n+20) {
            spec=1;
        } else {
            db[sum]++;
        }
    }

    for (int i=n+100; i>=1; i--) {
        while (db[i]>=2) {
            db[i]-=2, db[i-1]++;
        }
        if (db[i]) {
            spec=1;
        }
    }

    if (db[0]>=3 || (db[0]==3 && spec)) {
        cout << "NO\n";
    } else {
        cout << "YES\n";
    }

    for (int i=0; i<=n+100; i++) {
        db[i]=0;
    }
    spec=0;
}
int main()
{
    ios_base::sync_with_stdio(false);
    int w;
    cin >> w;
    while (w--) {
        solve();
    }
    return 0;
}
/*
1
8
1 1
1 2
2 1
1 3
2 2
3 1
1 4
2 3
*/
/*

1
9
1 1
1 2
2 1
1 3
2 2
3 1
1 4
2 3
100000000 100000000
*/