import sys
input = sys.stdin.readline

T=int(input())

for tests in range(T):
    N=int(input())

    L=[input().split() for i in range(N)]

    flag=0
    LEN=-1

    for i in range(N):
        if L[i][0]=="a":
            if "a" in L[i][1]:
                flag=1
                break
            else:
                LEN=max(LEN,len(L[i][1]))

    if flag:
        print("Yes")
        continue

    if LEN==-1:
        print("No")
        continue

    for i in range(N):
        if not ("a" in L[i][0]) and len(L[i][0])<=LEN:
            if "a" in L[i][1]:
                flag=1

            if len(L[i][1])>=len(L[i][0]):
                flag=1

    if flag:
        print("Yes")
    else:
        print("No")