n=int(input())
xy=[]
import sys
input=sys.stdin.readline #文字列入力はするな！

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

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

dis=[[0,0,0] for i in range(n*(n-1)//2)]
cnt=0
for i in range(n-1):
    for j in range(i+1,n):
        dis[cnt][0]=(xy[i][0]-xy[j][0])**2+(xy[i][1]-xy[j][1])**2
        dis[cnt][1]=i
        dis[cnt][2]=j
        cnt+=1
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)