n = int(input())
xy = [list(map(int, input().split())) for i in range(n)]
ans = n - 1
sx, sy = xy.pop(0)
xy.sort()
visited = [False] * (n - 1)
for i in range(n - 1):
    cur = (sx - xy[i][0]) ** 2 + (sy - xy[i][1]) ** 2
    for j in range(i, n - 1):
        if i != j:
            if (xy[i][0] - xy[j][0]) ** 2 + (xy[i][1] - xy[j][1]) ** 2 < cur and not visited[i] and not visited[j]:
                ans -= 2
                visited[i] = True
                visited[j] = True
                break
print(ans)