import sys
read = sys.stdin.readline
n = int(input())
x = [0] * n
y = [0] * n
for i in range(n):
    x[i], y[i] = map(int, read().split())


def dist(i, j):
    return (x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j])


# 取り除いた後に、取り除く必要があるやつが出てくる
#
ds = []
for i in range(1, n):
    ds.append((dist(0, i), i))
ds.sort()
ans = 0
used = [False] * n
for d, i in ds:
    need = True
    for j in range(1, n):
        if i == j or used[j]:
            continue
        e = dist(i, j)
        if d > e:
            need = False
            break
    if need:
        used[i] = True
        ans += 1
print(ans)