n=int(input())
xy=[]

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

    xy.append([x,y])
ans=0

dis=[]
for i in range(n-1):
    for j in range(i+1,n):
        dis.append([(xy[i][0]-xy[j][0])**2+(xy[i][1]-xy[j][1])**2,i,j])
dis.sort()
erase=[0]*(n)
for i in range(len(dis)):
    if dis[i][1]==0:
        if erase[dis[i][2]]==0:
            ans+=1
            erase[dis[i][2]]=1
    else:
        if erase[dis[i][1]]==erase[dis[i][2]]==0:
            erase[dis[i][1]] = erase[dis[i][2]]=1

print(ans)