import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(1000005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# md = 10**9+7
md = 998244353

def arg_sort(xy):
    def msort(xx):
        if not xx: return
        n = len(xx)
        a = [xx, xx[:]]
        lr = [(0, n, 1, 0)]
        while lr:
            l, r, f, g = lr.pop()
            m = (l+r)//2
            if f:
                lr.append((l, r, 0, g))
                if m-l > 1: lr.append((l, m, 1, g ^ 1))
                if r-m > 1: lr.append((m, r, 1, g ^ 1))
            else:
                i, j, p, q = l, m, m-1, r-1
                a1 = a[g]
                a2 = a[g ^ 1]
                for k in range((r-l)//2):
                    x, y = a2[i]
                    s, t = a2[j]
                    if s*y-t*x > 0:
                        a1[l+k] = a2[j]
                        j += 1
                    else:
                        a1[l+k] = a2[i]
                        i += 1
                    x, y = a2[p]
                    s, t = a2[q]
                    if s*y-t*x > 0:
                        a1[r-1-k] = a2[p]
                        p -= 1
                    else:
                        a1[r-1-k] = a2[q]
                        q -= 1
                if (r-l) & 1: a1[m] = a2[i] if i == p else a2[j]

    z1, z2, z3, z4, z5 = [], [], [], [], []
    for x, y in xy:
        if x == y == 0: z5.append((x, y))
        elif y >= 0:
            if x >= 0: z1.append((x, y))
            else: z2.append((x, y))
        else:
            if x < 0: z3.append((x, y))
            else: z4.append((x, y))

    msort(z1)
    msort(z2)
    msort(z3)
    msort(z4)

    return z1+z2+z3+z4+z5

n = II()
xy = LLI(n)

def ok(st):
    for i in range(n-2):
        x, y = st[i]
        s, t = st[i+1]
        if x*t-s*y == 0 and x*s >= 0 and y*t >= 0: return True
    return False

ans = 0
for x, y in xy:
    st = [(s-x, t-y) for s, t in xy if s != x or t != y]
    st = arg_sort(st)
    ans += ok(st)

print(ans)