from __future__ import annotations
import sys
from itertools import permutations
input = sys.stdin.readline


class Vector2:
	def __init__(self, x, y):
		self.x = x
		self.y = y

	def __str__(self):
		return str((self.x, self.y))

	__repr__ = __str__

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

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

	def __add__(self, other):
		return Vector2(self.x + other.x, self.y + other.y)

	def __sub__(self, other):
		return Vector2(self.x - other.x, self.y - other.y)

	def __mul__(self, other):
		return self.x * other.y - self.y * other.x

	def normalize(self) -> Vector2:
		assert(self.x != 0 or self.y != 0)
		norm = self.x ** 2 + self.y ** 2
		self.x *= abs(self.x) / norm
		self.y *= abs(self.y) / norm
		return self


def sgn(x: int) -> int:
	if(x > 0):
		return 1
	if(x < 0):
		return -1
	return 0

def same_inclination(v1: Vector2, v2: Vector2) -> bool:
	return (v1 * v2 == 0 and (v1.x * v2.x > 0 or v1.y * v2.y > 0))


"""
Main Code
"""

N = int(input())
P = [Vector2(*map(int, input().split())) for _ in [0] * N]

if(N == 1):
	print(1)
	exit(0)

perm = [*permutations([*range(N)], 2)]
vec_lis = [[None]*N for _ in [0]*N]
for i, j in perm:
	vec_lis[i][j] = P[j] - P[i]

ans = N
dp = [[[N]*N for _ in [0]*N] for _ in [0]*(1 << N)]
for i, j in perm:
	dp[(1 << i) | (1 << j)][i][j] = 1

goal = (1 << N) - 1
for b_now in range(3, goal):
	for v_prev, v_now in perm:
		if(dp[b_now][v_prev][v_now] == N or not((b_now >> v_prev) & 1) or not((b_now >> v_now) & 1)):
			continue
		c_next = c_now = dp[b_now][v_prev][v_now]
		v1 = vec_lis[v_prev][v_now]
		for v_next1, v_next2 in perm:
			if((((b_now >> v_next1) & 1) and v_now != v_next1) or ((b_now >> v_next2) & 1)):
				continue
			b_next = b_now | (1 << v_next1) | (1 << v_next2)
			v2, v3 = vec_lis[v_now][v_next1], vec_lis[v_next1][v_next2]
			if(v_now == v_next1):
				c_next = c_now + 1 - same_inclination(v1, v3)
			else:
				d = same_inclination(v1, v2) + same_inclination(v2, v3)
				if(d == 0):
					d = (sgn(v1 * v2) == sgn(v2 * v3) == sgn(v1 * v3))
				c_next = c_now + 2 - d
			# print(b_now, b_next, v_prev, v_now, v_next1, v_next2, c_now, c_next)
			if(dp[b_next][v_next1][v_next2] <= c_next):
				continue
			dp[b_next][v_next1][v_next2] = c_next

ans = min(min(lis) for lis in dp[goal])
print(ans)