#!/usr/bin/env python3.8
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import numpy as np

N = int(readline())
m = map(int, read().split())
XY = zip(m, m)

U = 20100
R = 20
filled = np.zeros((U, U), np.bool)
coin = np.zeros((R + R + 1, R + R + 1), np.bool)
for x in range(R + R + 1):
    for y in range(R + R + 1):
        coin[x][y] = (x - R) ** 2 + (y - R) ** 2 < R * R

answer = 0
for x, y in XY:
    x += R
    y += R
    if filled[x][y]:
        continue
    answer += 1
    filled[x - R: x + R + 1, y - R: y + R + 1] |= coin
print(answer)