let n = Int(readLine()!)!
var dpTable = [Int](repeating: 0, count: 1000000+1)
dpTable[2] = 1 

func countDivisor(num: Int) -> Int {
  var i = 1
  var count = 0
  while i*i <= num {
    if num % i == 0 {
      if num == i*i {
        count += 1
      } else {
        count += 2
      }
    }
    i += 1
  }
  return count
}

if n > 2 {
  for it in 3...n {
   dpTable[it] = dpTable[it-1] + countDivisor(num: it-1)
  }
}

print(dpTable[n])