N = int(input())
points = [tuple(map(int,input().split())) for _ in range(N)]
points.sort()

from functools import cmp_to_key

def ccw(a,b,c):
  ax,ay = a
  bx,by = b
  cx,cy = c
  bx -= ax
  cx -= ax
  by -= ay
  cy -= ay
  crs = bx*cy-cx*by
  if crs > 0:return 1
  if crs < 0: return -1
  return 0


p = points.pop()

def cmp(a,b):
  return ccw(p, a, b)

points.sort(key=cmp_to_key(cmp))
points.append(p)

ccws=[ccw(points[i-2],points[i-1],points[i]) == -1 for i in range(N)]
if  all(ccws):
  print("Yes")
else:
  print("No")