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

#define pb                        push_back
#define mp                        make_pair
#define ff                        first
#define ss                        second
#define rep(i,a,b)                for(int i=(a);i<=(b);++i)
#define rer(i,b,a)                for(int i=(b);i>=(a);--i)
#define clr(x,_)                  memset(x,_,sizeof(x))
#define feach(c,_)                for(__typeof((c).begin()) _=(c).begin();_!=(c).end();++_)
#define all(_)                    _.begin(),_.end()
#define sz(_)                     (int(_.size()))
#define len(_)                    (int(_.length()))
#define T()                       int _;cin>>_;while(_--)
#define LB(_,x)                   (lower_bound(all(_),x)-(_.begin()))
#define UB(_,x)                   (upper_bound(all(_),x)-(_.begin()))
#define sq(x)                     ((x)*(x))
#define dist(x1,y1,x2,y2)         (sqrt(sq(x1-x2)+sq(y1-y2)))
#define area(x1,y1,x2,y2,x3,y3)   (abs((x1*(y2-y3) + x2*(y3-y1) + x3*(y1-y2))))
#define PI                        acos(-1.0)
#define cnt_1                      __builtin_popcountll
#define lg(x)                     (63-__builtin_clzll(x))
#define dig(x)                    (int(log10(double(x)))+1)
#define cil(a,b)                  (LL(ceil(double(a)/double(b))))
#define gc                        getchar//_unlocked

//traces
#define dg1(x)                cerr<<__FUNCTION__<<" : "<<__LINE__<<" : "#x" = "<<x<<endl;
#define dg2(x,y)              cerr<<__FUNCTION__<<" : "<<__LINE__<<" : "#x" = "<<x<<" | "#y" = "<<y<<endl;
#define dg3(x,y,z)            cerr<<__FUNCTION__<<" : "<<__LINE__<<" : "#x" = "<<x<<" | "#y" = "<<y<<" | "#z" = "<<z<<endl;
#define dg4(a,b,c,d)          cerr<<__FUNCTION__<<" : "<<__LINE__<<" : "#a" = "<<a<<" | "#b" = "<<b<<" | "#c" = "<<c<<" | "#d" = "<<d<<endl;
#define dg5(a,b,c,d,e)        cerr<<__FUNCTION__<<" : "<<__LINE__<<" : "#a" = "<<a<<" | "#b" = "<<b<<" | "#c" = "<<c<<" | "#d" = "<<d<<" | "#e" = "<<e<<endl;
#define dg6(a,b,c,d,e,f)      cerr<<__FUNCTION__<<" : "<<__LINE__<<" : "#a" = "<<a<<" | "#b" = "<<b<<" | "#c" = "<<c<<" | "#d" = "<<d<<" | "#e" = "<<e<<" | "#f" = "<<f<<endl;

typedef long long int LL;     typedef pair<int,int> PII;       typedef vector<int> VI;          typedef vector<PII> VPII;
typedef pair<LL,LL> PLL;      typedef vector<LL> VLL;          typedef vector<PLL> VPLL;        typedef vector<VPII> VVPII;

//utility functions
#define RG                   1
bool markP[RG];VI prime;
inline void sieve(){int i,j;for(i=2;i*i<=RG;++i)if(!markP[i])for(j=i<<1;j<RG;j+=i)if(!markP[j])markP[j]=1;prime.pb(2);for(i=3;i<RG;i+=2)if(!markP[i])prime.pb(i);}
inline void inp(int &x){register int c=gc();x=0;bool neg=0;for(;((c<48||c>57)&&c!='-');c=gc());if(c=='-'){neg=1;c=gc();}for(;c>47&&c<58;c=gc()){x=(x*10)+(c-48);}if(neg)x=-x;}
inline LL modexp(LL a,LL b,const LL &mod){LL x=1;a%=mod;while(b>0){if(b&1){x*=a;if(x>=mod)x%=mod;};b>>=1;a*=a;if(a>=mod)a%=mod;}return x;}
inline LL mulmod(LL a,LL b,const LL &mod){LL x=0;a%=mod;while(b>0){if(b&1){x+=a;if(x>=mod)x-=mod;}a<<=1;if(a>=mod)a%=mod;b>>=1;}return x;}
inline LL Pow(LL a,LL b){LL x=1;while(b>0){if(b&1)x=(x*a);a*=a;b>>=1;}return x;}
inline LL toNum(const string &st){LL num;stringstream ss(st);ss>>num;return num;}
inline LL strmod(const string &T,const LL &mod){LL mul=0;rep(i,0,len(T)-1){mul=(mul*10+T[i]-'0');if(mul>=mod)mul%=mod;}return mul;}
inline LL fib(LL n,const int &mod){LL i,j,h,k,t;i=h=1;j=k=0;while(n>0){if(n&1){t=j*h%mod;j=(i*h+j*k+t)%mod;i=(i*k+t)%mod;}t=h*h%mod;h=(2*k*h+t)%mod;k=(k*k+t)%mod;n>>=1;}return j;}
inline LL comb(const LL &N,LL R,const LL &mod){if(R>N) return 0;R>(N-R)?(R=N-R):R;LL mul=1LL;rep(i,0,R-1) mul=((mul*(N-i))%mod*modexp(i+1,mod-2,mod))%mod;return mul;}
inline bool cmp(const PII &X,const PII &Y) {return (X.ff!=Y.ff)?(X.ff<Y.ff):(X.ss<Y.ss);}

#define MOD                  1000000007
#define MX                   200007


int main(){
	ios_base::sync_with_stdio(false);
	//freopen("inp.txt","r",stdin);
	//freopen("out.txt","w",stdout);
	int q,n,x,y;
	cin>>q;
	while(q--){
		cin>>n;
		map<int,int> mx, my;
		if(n<=2){
			cout<<"YES\n";
			continue;
		}
		rep(i,1,n){ 
			cin>>x>>y;
			m[x]++;
			m[y]++;
		}
        cout<< "YES\n;
	}
    return 0;
}