import sys
import pprint

def main():
    n = int(input())
    stars = []
    for i in range(n):
        x, y = [int(i) for i in input().split()]
        stars.append((x, y))

    def punkce(x, y):
        return (stars[x][0] - stars[y][0], stars[x][1] - stars[y][1])

    mjapa = {}
    sliz = len(stars)

    for y in range(sliz):
        for x in range(sliz):
            if x != y:
                diff = punkce(x, y)
                if not diff in mjapa:
                    mjapa[diff] = set()
                mjapa[diff].add(x)
                mjapa[diff].add(y)
   
    #pprint.pprint(mjapa)

    result = 0
    for mj in mjapa.values():
        if len(mj) == sliz:
            result += 1

    print(result)

    
main()