import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 7)


def touch(x, y, xx, yy):
    return (x - xx) ** 2 + (y - yy) ** 2 >= 20 * 20


N = int(input())
XY = tuple(tuple(map(int, input().split())) for _ in range(N))
ans = 0

B = [[set() for _ in range(1001)] for _ in range(1001)]
for i, (x, y) in enumerate(XY):
    xx = x // 100
    yy = y // 100
    ok = True
    for l in range(-1, 2):
        for r in range(-1, 2):
            for xi, yi in B[l][r]:
                ok &= touch(x, y, xi, yi)
    if ok:
        ans += 1
        B[xx][yy].add((x, y))

print(ans)