def convex_hull(points):
    def is_anticlockwise(i,j,k):
        """
        i,j,k がこの向きで反時計回りなら true
        """
        xi,yi = points[i]
        xj,yj = points[j]
        xk,yk = points[k]
        return (xj-xi)*(yk-yj) > (yj-yi)*(xk-xj) 

    n = len(points)
    points.sort()
    size = 0
    lst = []
    for i in range(n):
        while size > 1:
            if is_anticlockwise(lst[-2],lst[-1],i):
                break
            size -= 1
            lst.pop()
        lst.append(i)
        size += 1

    size = 0
    for i in range(n-1)[::-1]:
        while size:
            if is_anticlockwise(lst[-2],lst[-1],i):
                break
            size -= 1
            lst.pop()
        lst.append(i)
        size += 1
    return lst[:-1]

xy = [tuple(map(int,input().split())) for _ in range(5)]
lst = convex_hull(xy)
print("YES" if len(lst)==5 else "NO")