q = int(input())

for i in range(q):
    n = int(input())
    X = [1] * n
    Y = [1] * n
    for j in range(n):
        x,y = [int(k) for k in input().strip().split()]
        X[j] = x
        Y[j] = y
        
    xmax = max(X)
    xmin = min(X)
    ymax = max(Y)
    ymin = min(Y)
    
    for k in range(n):
        if not (X[k]==xmax or X[k]==xmin or Y[k]==ymax or Y[k]==ymin):
            print("NO")
            break
        if k == (n-1):
            print("YES")