n=int(input())

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

dist=[]
for i in range(n):
    tmp=[]
    for j in range(n):
        if i==j:
            continue
        d=(coord[i][0]-coord[j][0])**2+(coord[i][1]-coord[j][1])**2
        tmp.append((d, j))
    tmp=sorted(tmp)
    dist.append(tmp)

cnt=0
removed=set([])
for i in range(1,n):
    for j in range(n-1):
        x=dist[i][j][1]
        if i in removed:
            break
        elif x in removed:
            continue
        elif x==0:
            removed.add(i)
            cnt+=1
        else:
            removed.add(x)
            removed.add(i)
            break

print(cnt)