#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------

int T,N;
string X[101010],Y[101010];

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>T;
	while(T--) {
		cin>>N;
		int mask=0;
		int num=0;
		int mul=0;
		FOR(i,N) {
			cin>>X[i]>>Y[i];
			if(X[i]=="a") {
				if(count(ALL(Y[i]),'a')) {
					mask=1;
				}
				else {
					num=max(num,(int)Y[i].size());
				}
			}
		}
		
		FOR(i,N) {
			if(count(ALL(X[i]),'a')==0&&num>=X[i].size()) mask=1;
		}
		
		if(mask) cout<<"Yes"<<endl;
		else cout<<"No"<<endl;
		
	}
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}