from math import ceil,sqrt
from heapq import *

N=int(input())
point=[tuple(map(int,input().split())) for _ in range(N)]

d=set()
res=0

def off(a,b,c):
    return a*10**19+b*10**9+c
def get(x):
    a=x//10**19
    x%=10**19
    b=x//10**9
    x%=10**9
    return a,b,x

G=[]
for i in range(N):
    que=[]
    for j in range(N):
        if i==j:
            continue
        xi,yi=point[i]
        xj,yj=point[j]
        dist=sqrt((xi-xj)**2+(yi-yj)**2)
        d.add(off((ceil(dist)+1)//2,min(i,j),max(i,j)))
d=sorted(d)

delete=set()

for x in d:
    t,i,j=get(x)
    if i in delete or j in delete:
        continue
    if i!=0 and j!=0:
        delete.add(i)
        delete.add(j)
    elif i==0:
        delete.add(j)
        res+=1
    elif j==0:
        delete.add(i)
        res+=1
print(res)