def distance(X, Y):
    return abs(X[0] - Y[0])**2 + abs(X[1] - Y[1])**2

n = int(input())
xy = [list(map(int, input().split())) for _ in range(n)]
d = []

for i in range(n):
    for g in range(i+1, n):
        d.append((distance(xy[i], xy[g]), (i, g)))
d.sort()

delete = set()
exploded = set()
cnt = 0
used = [False]*n

for i, x in d:
    if (x[0] in delete) or (x[1] in delete) or (x[0] in exploded) or (x[1] in exploded):
        continue
    if x[0] == 0:
        delete.add(x[1])
    else:
        exploded.add(x[0])
        exploded.add(x[1])
print(len(delete))