from collections import defaultdict, deque
import sys
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2**63-1
mod = 998244353
import sys
from collections import deque
from fractions import Fraction as frac
input = sys.stdin.readline
INF = 10 ** 9

class Point:
	def __init__(self, x: frac, y: frac):
		self.x = x
		self.y = y

	def __eq__(self, other):
		return (self.x == other.x and self.y == other.y)

	def __hash__(self):
		return hash((self.x, self.y))

	def __lt__(self, other):
		if(self.x == other.x):
			return (self.y < other.y)
		return (self.x < other.x)

	def show(self):
		print(self.x, self.y)

	def calcLine(self, other):
		x1 = self.x;  y1 = self.y
		x2 = other.x;  y2 = other.y
		if(x1 == x2):
			return Line(frac(1), frac(0), x1)
		a = (y1 - y2) / (x1 - x2)
		c = y1 - a * x1
		return Line(-a, frac(1), c)
class Line:
	def __init__(self, a: frac, b:frac, c:frac):
		self.a = a
		self.b = b
		self.c = c

	def __eq__(self, other):
		return (self.a == other.a and self.b == other.b and self.c == other.c)

	def __hash__(self):
		return hash((self.a, self.b, self.c))

	def show(self):
		print((self.a, self.b, self.c))

	def intersection(self, other) -> Point:
		p = self.a * other.b - other.a * self.b
		if(p == frac(0)):
			return None
		q = other.b * self.c - self.b * other.c
		x = q / p
		y = (other.c - other.a * x) / other.b if(self.b == 0) else (self.c - self.a * x) / self.b
		return Point(x, y)
n = ii()

XY = [li() for _ in range(n)]

dp = [[defaultdict(lambda:inf) for _ in range(n)] for _ in range(2**n)]
q = deque()
for i in range(n):
    dp[2**i][i][(Line(-inf, -inf, -inf), 0)] = 0
    q.append((2**i,i,(Line(-inf, -inf, -inf), 0)))

while q:
    bit, now, l = q.popleft()
    if bit == ((2**n) - 1):
        print(dp[bit][now][l])
        break
    for to in range(n):
        if now == to:
            continue
        l2 = (Point(*XY[now]).calcLine(Point(*XY[to])), XY[now] < XY[to])
        if l == l2:
            if dp[bit ^ (2**to)][to][l] > dp[bit][now][l]:
                dp[bit^(2**to)][to][l] = dp[bit][now][l]
                q.appendleft((bit^(2**to), to, l))
        else:
            if dp[bit ^ (2**to)][to][l2] > dp[bit][now][l] + 1:
                dp[bit^(2**to)][to][l2] = dp[bit][now][l] + 1
                q.append((bit^(2**to), to, l2))