q = int(input())
for z in range(q):
    n = int(input())
    X = []
    Y = []
    for q in range(n):
        x, y = list(map(int,input().split()))
        X.append(x)
        Y.append(y)
    x1 = min(X)
    x2 = max(X)
    y1 = min(Y)
    y2 = max(Y)
    
    if n == 1:
        print('YES')
    else:
        answer = 'YES'
        for i in range(n):
            Xcour = X[i]
            Ycour = Y[i]
            
            if (Xcour == x1 or Xcour == x2) and (y1 <= Ycour and Ycour <= y2):
                pass
            elif (Ycour == y1 or Ycour == y2) and (x1 <= Xcour and Xcour <= x2):
                pass
            else:
                answer = 'NO'
        print(answer)