private fun getInts(): IntArray {
    return readLine()!!.split(" ").map {it.toInt()}.toIntArray()
}

fun main(){
    val n = getInts()[0]
    var a = 1
    var b = n
    var count =0
    while(a<n && b>0) {
        while(a*b >= n){
            b--
        }
        count += b
        a++
    }
    print (count)
}