// Problem: D - Subgraph Isomorphism
// Contest: Virtual Judge - 过什么520做题要紧
// URL: https://vjudge.net/contest/559671#problem/D
// Memory Limit: 1024 MB
// Time Limit: 3000 ms
// Date:2023-05-20 07:53:15
// By:SmallBlack
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
using namespace std;
inline long long read()
{
	long long s=0,k=1;
	char c=getchar();
	while(!isdigit(c))
	{
		k=(c=='-')?-1:1;
		c=getchar();
	}
	while(isdigit(c))
	{
		s=s*10+c-'0';
		c=getchar();
	}
	return s*k;
}
#define d read()
#define ll long long
#define ull unsigned long long
#define Maxn 10010
#define Size 100010
#define mp make_pair
#define pb push_back
#define fi first
#define se second
vector<ll>e[Size];
vector<ll>st,loop;
bool ins[Size],fin=0;
void dfs(ll u,ll fa)
{
	ins[u]=1,st.pb(u);
	for(auto v:e[u])
	{
		if(v==fa) continue;
		if(ins[v])
		{
			while(st.back()!=v)
			{
				loop.pb(st.back());
				st.pop_back();
			}
			loop.pb(v);
			fin=1;
			return;
		}
		dfs(v,u);
		if(fin) return;
	}
	st.pop_back(),ins[u]=0;
}
const ull mask=std::chrono::steady_clock::now().time_since_epoch().count();
ull shift(ull x)
{
	x=x^mask^((x^mask)<<13),x^=x>>7,x^=x<<17;
	return x^mask;
}
ull tag[Size];
ull ksm(ull a,ull b)
{
	ull ans=1;
	while(b)
	{
		if(b&1) ans=ans*a;
		a=a*a,b>>=1;
	}
	return ans;
}
void Hash(ll u,ll fa)
{
	tag[u]=1;
	for(auto v:e[u])
	{
		if(v==fa||ins[v]) continue;
		Hash(v,u);
		tag[u]+=ksm(tag[v],20070529);
	}
}
void solve()
{
	ll n=d,m=d;
	for(int i=1;i<=n;i++) e[i].clear(),ins[i]=0,tag[i]=0;
	for(int i=0;i<m;i++)
	{
		ll x=d,y=d;
		e[x].pb(y),e[y].pb(x);
	}
	if(m==n-1) return (void)puts("YES");
	else if(m>n) return (void)puts("NO");
	fin=0,st.clear(),loop.clear(),dfs(1,0);
	for(int i=1;i<=n;i++) ins[i]=0;
	for(auto x:loop) ins[x]=1;
	if(loop.size()==n) return (void)puts("YES");
	ll cnt=0;
	for(auto x:loop) Hash(x,0),cnt+=(int)(tag[x]!=1);
	if(cnt==1) return (void)puts("NO");
	unsigned ll same=0;
	ll fir=-1,last=-1,dis=-1;
	for(int i=0;i<loop.size();i++)
	{
		if(tag[loop[i]]==1) continue;
		if(same==0) same=tag[loop[i]];
		else if(same!=tag[loop[i]])
			return (void)puts("NO");
		if(fir==-1) fir=i;
		if(last==-1) last=i;
		else if(dis==-1) dis=i-last,last=i;
		else if(dis!=i-last)
			return (void)puts("NO");
		else last=i;
	}
	if(dis!=fir+loop.size()-last) return (void)puts("NO");
	if(dis>2) return (void)puts("NO");
	puts("YES");
}
int main()
{
	ll t=d;
	while(t--) solve();
}