for t in range(int(input())):
    n = int(input())
    X = []
    Y = []
    ts = []
    for i in range(n):
        x,y = [int(x) for x in input().split()]
        ts.append((x,y))
        X.append(x)
        Y.append(y)
    maxX = max(X)
    maxY = max(Y)
    minX = min(X)
    minY = min(Y)

    cbd = True
    for p in ts:
        if(p[0] == maxX or p[0] == minX):
            if(p[1] >= minY and p[1] <= maxY):
                cbd = True
            else:
                cbd = False
                break
        else:
            if(p[1] == minY or p[1] == maxY):
                cbd = True
            else:
                cbd = False
                break
        
    if(cbd):
        print("YES")
    else:
        print("NO")