import itertools

n = int(input())

balloons = []
for _ in range(n):
    x, y = map(int,input().split())
    balloons.append((x, y))

dist = []
for a, b in itertools.combinations([i for i in range(n)], 2):
    x1, y1 = balloons[a]
    x2, y2 = balloons[b]
    d = (x2-x1)**2+(y2-y1)**2
    dist.append((d, a, b))
    
dist.sort()

removed = [0]*n
ans = 0
for d in dist:
    a = d[1]
    b = d[2]
    if a == 0:
        if removed[b] == 0:
            ans += 1
            removed[b] = 1
    else:
        if removed[a] == 0 and removed[b] == 0:
            removed[a] = 1
            removed[b] = 1

print(ans)