from math import gcd
from collections import defaultdict
import sys
input = sys.stdin.readline

n = int(input())
P = [list(map(int, input().split())) for _ in range(n)]

ans = 0
for i in range(n):
    xi, yi = P[i]
    counter = defaultdict(int)
    flag = False
    for j in range(n):
        if i == j:
            continue
        xj, yj = P[j]
        dx, dy = abs(xi - xj), abs(yi - yj)
        gcd_ = gcd(dx, dy)
        dx, dy = dx // gcd_, dy // gcd_
        plus_x = (xj >= xi)
        plus_y = (yj >= yi)
        counter[dx, dy, plus_x, plus_y] += 1
        if counter[dx, dy, plus_x, plus_y] == 2:
            flag = True
            break
    if flag:
        ans += 1
print(ans)