import sys
import itertools
import math
def S(): return sys.stdin.readline().rstrip()
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())

n = I()
x = []
y = []
d = []

for i in range(n):
    a,b = MI()
    x.append(a)
    y.append(b)

for i in range(1, n):
    for j in range(i):
        tmp = (x[i]-x[j])**2 + (y[i]-y[j])**2
        d.append([tmp, i, j])

d.sort()

deleted = []
ans = 0

for i in d:
    if i[1] == 0:
        if i[2] not in deleted:
            deleted.append(i[2])
            ans += 1
    elif i[2] == 0:
        if i[1] not in deleted:
            deleted.append(i[1])
            ans += 1
    else:
        if (i[1] not in deleted) and (i[2] not in deleted):
            deleted.append(i[1])
            deleted.append(i[2])

print(ans)