from collections import deque
import sys
input=sys.stdin.readline

def dist(P,Q):
    a,b=P[0]-Q[0],P[1]-Q[1]
    return a*a+b*b

N=int(input())
P=[0]*N

for i in range(N):
    P[i]=tuple(map(int,input().split()))

Q=[0]*(N*(N-1)//2)
k=0
for i in range(N):
    for j in range(i+1,N):
        Q[k]=(dist(P[i],P[j]),j,i)
        k+=1

Q.sort()
Q=deque(Q)
Flag=[True for _ in range(N)]

X=0
while Q:
    (_,j,i)=Q.popleft()

    if not(Flag[i] and Flag[j]):
        continue

    Flag[j]=False
    if i!=0:
        Flag[i]=False
    else:
        X+=1
print(X)