import java.util.*

fun main() {
    val builder = StringBuilder()

    val n = readInputLine().toInt()

    val balloon = Array(n) {
        val (x, y) = readInputLine().split(" ").map { it.toLong() }
        Pair(x, y)
    }

    val queue = PriorityQueue<Triple<Int, Int, Long>> { x, y -> x.third.compareTo(y.third) }

    for (i in 0 until n) {
        for (j in i + 1 until n) {
            val x = balloon[i].first - balloon[j].first
            val y = balloon[i].second - balloon[j].second
            queue.add(Triple(i, j, x * x + y * y))
        }
    }

    var ans = 0
    val removed = BooleanArray(n)

    while (queue.isNotEmpty()) {
        val (x, y, _) = queue.poll()!!

        if (removed[x] || removed[y]) {
            continue
        }

        if (x == 0 && !removed[y]) {
            ans++
        }
        if (x != 0) {
            removed[x] = true
        }
        removed[y] = true
    }

    builder.appendln(ans)

    print(builder.toString())
}

fun readInputLine(): String {
    return readLine()!!
}