#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int t;
    cin >> t;
    while(t--) {
        int n;
        cin >> n;
        // a -> a 含んでたらOK
        // a -> bbbb m   n < m no bbbbかつa含むOK
        bool ans = false;
        int c = 0;
        int mc = 1e9;
        rep(i,n) {
            string x, y;
            cin >> x >> y;
            if(x=="a") {
                for(char c : y) if(c=='a') ans = true;
                if(!ans) {
                    c = max(c, (int)y.size());
                }
            }
            bool ex = true;
            for(char c : x) if(c=='a') ex = false;
            if(ex) {
                for(char c : y) if(c=='a') {
                    mc = min(mc, (int)x.size());
                }
            }
        }
        dbg(c,mc);
        if(ans || c>=mc) {
            cout << "Yes" << endl;
        }
        else{
            cout << "No" << endl;
        }
    }
    return 0;
}