output_description: Print "1" or "0" in a line.
input_description: g is given by coordinates of the points p1,..., pn in the following format:
  
      
      
      n
      x1 y1 
      x2 y2
      :
      xn yn
      
  
  The first integer n is the number of points. The coordinate of a point pi is
  given by two integers xi and yi. The coordinates of points are given in the
  order of counter-clockwise visit of them.
attempt: n = int(input())
  vec = []
  for i in range(n):
      vec += [list(map(int, input().split()))]
  vec += [vec[0]]
  vec += [vec[1]]
  Sum = 0
  
  
  def cross(a, b):
      return a[0] * b[1] - a[1] * b[0]
  
  
  def ab(a, b):
      c = (b[0] - a[0], b[1] - a[1])
      return c
  
  
  def check(a, b, c):
      if cross(ab(a, b), ab(a, c)) >= 0:
          return 1
      else:
          return 0
  
  
  for a, b, c in zip(vec[0:-2], vec[1:-1], vec[2:]):
      cnt = check(a, b, c)
      if cnt == 0:
          break
  print(cnt)
  
problem_description: Is-Convex
  
    
  
  For a given polygon g, print "1" if g is a convex polygon, "0" otherwise.
  Here, in a convex polygon, all interior angles are less than or equal to 180
  degrees.
  
  g is represented by a sequence of points p1, p2,..., pn where line segments
  connecting pi and pi+1 (1 ≤ i ≤ n-1) are sides of the polygon. The line
  segment connecting pn and p1 is also a side of the polygon.
samples: [{"input": "4\n    0 0\n    3 1\n    2 3\n    0 3", "output": "1"}, {"input": "5\n    0 0\n    2 0 \n    1 1\n    2 2\n    0 2", "output": "0"}]