def main():
    n = int(input())
    XY = [tuple(map(str, input().split())) for _ in range(n)]
    m = 0
    t = 0
    for x, y in XY:
        if x == "a":
            if "a" in y:
                return "Yes"
            else:
                m = max(m, len(y))
    for x, y in XY:
        if not "a" in x and len(x) <= m:
            if len(x) < len(y):
                return "Yes"
            elif "a" in y:
                return "Yes"
    return "No"

for _ in range(int(input())):
    print(main())