import sys
input = sys.stdin.readline
T = int(input())
INF = 10**9
for _ in range(T):
    N = int(input())
    XY = [input().split() for _ in range(N)]
    flag = False
    Y = 0
    X = INF
    for x, y in XY:
        if x=="a":
            if "a" in y:
                flag = True
                break
            else:
                if Y<len(y):
                    Y = len(y)
        else:
            if "a" not in x:
                if X>len(x):
                    X = len(x)
    if flag:
        print("Yes")
        continue
    
    if Y>=X:
        print("Yes")
    else:
        print("No")