#include
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double db;
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// #define ordered_set tree<ll, null_type,less, rb_tree_tag,tree_order_statistics_node_update>
#define pll pair<ll, ll>
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define ub(v, val) upper_bound(v.begin(), v.end(), val)
#define np(str) next_permutation(str.begin(), str.end())
#define lb(v, val) lower_bound(v.begin(), v.end(), val)
#define sortv(vec) sort(vec.begin(), vec.end())
#define rev(p) reverse(p.begin(), p.end());
#define v vector
#define pi 3.14159265358979323846264338327950288419716939937510
#define len length()
#define repc(i, s, e) for (ll i = s; i < e; i++)
#define fi first
#define se second
#define mset(a, val) memset(a, val, sizeof(a));
#define mt make_tuple
#define repr(i, n) for (i = n - 1; i >= 0; i–)
#define rep(i, n) for (i = 0; i < n; i++)
#define IOS
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
#define at(s, pos) *(s.find_by_order(pos))
#define set_ind(s, val) s.order_of_key(val)
long long int M = 1e9 + 7;
long long int inf = 9 * 1e18;
//CLOCK
ll begtime = clock();
#define time() cout << “\n\nTime elapsed: " << (clock() - begtime) * 1000 / CLOCKS_PER_SEC << " ms\n\n”;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//CLOCK ENDED
ll n, m;
// modular exponentiation
ll binpow(ll val, ll deg)
{
if (deg < 0)
return 0;
if (!deg)
return 1 % M;
if (deg & 1)
return binpow(val, deg - 1) * val % M;
ll res = binpow(val, deg >> 1);
return (res * res) % M;
}
//binomial
ll modinv(ll n)
{
return binpow(n, M - 2);
}
//GCD
ll gcd(ll a, ll b)
{
if (b == 0)
return a;
else
return gcd(b, a % b);
}
int main()
{
// your code goes here
IOS;
// #ifndef ONLINE_JUDGE
// freopen(“input.txt”, “r”, stdin);
// freopen(“output.txt”, “w”, stdout);
// #endif
ll i, j, t, k, x, y, z, n, N, T;
cin >> t;
while (t–)
{
cin >> n;
map<ll, ll> mp;
rep(i, n)
{
cin >> x >> y;
mp[(x + y)]++;
}
ll flg = 0;
repc(i, 2, n + 2)
{
if (mp[i] == (i - 1))
{
flg = 1;
// break;
}
}
if (!flg)
{
ll curr = n - 1;
repc(i, n + 2, 2 * n + 1)
{
if (mp[i] == curr)
{
flg = 1;
// break;
}
curr–;
}
if (flg)
cout << “NO” << endl;
else
cout << “YES” << endl;
}
else
cout << “NO” << endl;
}
return 0;
}
