import kotlin.math.floor
import kotlin.math.sqrt

fun main() {
    val n = readLine()!!.toInt()
    var sum = 0L
    for (a in 1..floor(sqrt(n.toDouble())).toInt()) {
        for (b in a..n) {
            if (a*b >= n) {
                break
            }
            sum += if (a == b) 1 else 2
        }
    }
    println(sum)
}