q = int(input())
for iter in range(q):
    points = []
    xDict = {}
    yDict = {}
    n = int(input())
    if n == 2:
        (a,b) = input().split()
        (c,d) = input().split()
        if a == c or b == d:
            print("YES")
        else:
            print("NO")
    else:
        for i in range(n):
            (x,y) = input().split()
            (x,y) = (int(x),int(y))
            points.append((x,y))
            if x in xDict:
                xDict[x] += 1
            else:
                xDict[x] = 1
            if y in yDict:
                yDict[y] += 1
            else:
                yDict[y] = 1
     
        flag = True
        for (x,y) in points:
            if (xDict[x] > 1 and y <= max(yDict)) or (yDict[y] > 1 and x <= max(xDict)):
                pass
            else:
                print("NO")
                flag = False
                break
        if flag:
            print("YES")