import sys
from operator import itemgetter
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())

N = I()
XY = [()] * N
for i in range(N):
    x, y = MI()
    XY[i] = (x, y)

edges = []
for i, (x, y) in enumerate(XY):
    for j, (x2, y2) in enumerate(XY[i+1:], i+1):
        dist = (x-x2)**2 + (y-y2)**2
        edges.append((dist, i, j))

edges.sort(key=itemgetter(0))
removed = [0] * N
ans = 0
for dist, a, b in edges:
    if removed[a] or removed[b]:
        continue
    if a == 0:
        ans += 1
        removed[b] = 1
    elif b == 0:
        ans += 1
        removed[a] = 1
    else:
        removed[a] = 1
        removed[b] = 1
print(ans)