'''
n, m = map(int, input().split())

who_can = [[i] for i in range(n)]

for i in range(m):
    worker = input().split()
    for j in range(n):
        if worker[j] != '0':
            who_can[j].append(i)
'''


def on_one_line(x1, y1, x2, y2, x3, y3):
    return (x1-x2)*x3 + (y1-y2)*y3 == 0


def rotate(A,B,C):
    return (B[0]-A[0])*(C[1]-B[1])-(B[1]-A[1])*(C[0]-B[0])


def jarvismarch(A):
    n = len(A)

    counter = 0

    P = [i for i in range(n)]

    for i in range(1,n):
      if A[P[i]][0]<A[P[0]][0]:
        P[i], P[0] = P[0], P[i]

    H = [P[0]]
    del P[0]
    P.append(H[0])

    while True:
      right = 0
      for i in range(1,len(P)):

        if rotate(A[H[-1]], A[P[right]], A[P[i]]) < 0:
          right = i

      if P[right] == H[0]:
        break

      else:
        if not on_one_line(A[H[-3]][0], A[H[-3]][1], A[H[-2]][0], A[H[-2]][1], A[H[-1]][0], A[H[-1]][1]):
            counter += 1
        H.append(P[right])
        del P[right]
    return H, counter


n = int(input())
A = []
point = [0, 0]
for i in range(n):
    A.append([int(el) for el in input().split()])

answ, wrong = jarvismarch(A)
print((n - 1)*(len(answ)-wrong)