q = int(input())
for t in range(q):
    n = int(input())
    data = []
    for i in range(n):
        data.append([int(x) for x in input().split()])
    answer = 'YES'
    minx = min(data, key=lambda x: x[0])[0]
    maxx = max(data, key=lambda x: x[0])[0]
    miny = min(data, key=lambda x: x[1])[1]
    maxy = max(data, key=lambda x: x[1])[1]
    for p in data:
        if minx < p[0] < maxx and miny < p[1] < maxy:
            answer = 'NO'
            break
            
    print(answer)