import sys
input = sys.stdin.readline

N=int(input())
ANS=0

LIST=[[[] for j in range(100)] for i in range(100)]

for i in range(N):
    x,y=map(int,input().split())

    k=x//250
    l=y//250

    flag=1

    for s in [k,k-1,k+1]:
        for t in [l,l-1,l+1]:
            if 0<=s<100 and 0<=t<100:
                for z,w in LIST[s][t]:
                    if (x-z)**2+(y-w)**2<400:
                        flag=0

    if flag==1:
        ANS+=1
        LIST[k][l].append((x,y))

print(ANS)