#include<bits/stdc++.h>
#define TLE {int sum=0;for(int i=0;i<1e10;i++)sum+=i;cout<<sum;}
#define int long long
#define endl '\n'
#define rep(i, x, y) for(int i=(x), _=(y);i<=_;i++)
#define rrep(i, x, y) for(int i=(x), _=(y);i>=_;i--)
using namespace std;
const int mod = 998244353;
const double eps = 1e-6;

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

inline int read(){int c;cin>>c;return c;}
inline void readn(int a[], int n){
    for_each(a + 1, a + n + 1, [](int &x){cin>>x;});
}
inline void printn(int a[], int n){
	for_each(a + 1, a + n + 1, [](int &x){
		cout<<x<<' ';
	});
	cout<<endl;
}
template<typename T, typename... Args>
void print(const T& first, const Args&... args) {
    cout << first;
    ((cout << ' ' << args), ...);
    cout << endl;
}
template<typename T, typename... Args>
void eprint(const T& first, const Args&... args) {
	cerr<<'*';
    cerr << first;
    ((cerr << ' ' << args), ...);
    cerr << endl;
}
#define eprintn(a, n) cerr << #a << ' ';\
for(int i=1;i<=n;i++)\
	cerr<<(a)[i]<<' ';\
cerr<<endl;

const int N=1e6 + 20,M=N*2;

int n, m, k;
char out[2][10] = {"No", "Yes"};
int a[N], b[N];
vi edge[N];
void addEdge(int u, int v){
	edge[u].push_back(v);
	edge[v].push_back(u);
}
int fa[N];
int get(int u){
	return u == fa[u] ? u : fa[u] = get(fa[u]);
}

signed main(){
	cin.tie(0)->sync_with_stdio(0);
	for(int T=read();T--;){
		int n = read();
		int ans = 1;
		iota(fa, fa + n + 1, 0);
		rep(i, 1, n){
			int l = read(), r = read() + 1;
			l = get(l), r = get(r);
			if(l == r){
				ans = 0;
			}else{
				fa[l] = r;
			}
		}
		print(ans);
	}
}