N = int(raw_input())
circle = [map(int,raw_input().split()) for i in range(N)]
exist = [True for i in range(N)]
n = N
for i in range(N):
	for j in range(0,i):
		if not exist[j]:continue
		if ((circle[i][0] - circle[j][0])*(circle[i][0] - circle[j][0])) + ((circle[i][1] - circle[j][1])*(circle[i][1] - circle[j][1])) >= 400:continue
		exist[i] = False
		n -= 1
print n