def solve():
    
    n = int(input())
    p = []
    x1 = 100000
    x2 = -100000
    y1 = 100000
    y2 = -100000
    for i in range(n):
        x, y = map(int, input().split())
        x1 = min(x1, x)
        x2 = max(x2, x)
        y1 = min(y1, y)
        y2 = max(y2, y)
        p.append([x,y])
    
    if x1 == x2 or y1 == y2:
        return "YES"
    
    if n <= 2:
        return "YES"
    
    for i in range(n):
        if p[i][1] == y1 or p[i][1] == y2:
            pass
        elif  p[i][0] == x1 or p[i][0] == x2:
            pass
        else:
            return "NO"
    return "YES"


for i in range(int(input())):
    print(solve())