import math

def get_angle(pt):
    return math.atan2(pt[1], pt[0])

def sort_points_clockwise(points):
    center = (sum(x for x, y in points) / len(points), sum(y for x, y in points) / len(points))
    return sorted(points, key=lambda point: -get_angle((point[0]-center[0], point[1]-center[1])))

points = [(985, 268), (112, 316), (998, 448), (1018, 453), (1279, 577), (1196, 477), (1161, 443), (986, 0), (830, 0), (983, 230), (998, 425), (998, 255)]
N=int(input())
L=[]
a=0
b=0
for i in range(N):
  x,y=map(int,input().split())
  L.append((x,y))
h = sort_points_clockwise(L)
result='Yes'
for i in range(N):
  a,b,c=h[i%N],h[(i+1)%N],h[(i+2)%N]
  d,e=[b[0]-a[0],b[1]-a[1]],[c[0]-b[0],c[1]-b[1]]
  score=d[0]*e[1]-d[1]*e[0]
  if score>=0:
    result='No'
print(result)