N = int(raw_input())
X = [0 for i in range(N)]
Y = [0 for i in range(N)]
exist = [True for i in range(N)]
for i in range(N):
	X[i],Y[i] = map(int,raw_input().split())
for i in range(N):
	for j in range(0,i):
		if not exist[j]:continue
		if ((X[i] - X[j])*(X[i] - X[j])) + ((Y[i] - Y[j])*(Y[i] - Y[j])) >= (10+10)*(10+10):continue
		exist[i] = False
print exist.count(True)