const main = stdin => {
  const input = stdin.trim().split('\n')
  const N = parseInt(input[0])
  let c = 0
  for (let i = N - 1; i >= 1; i--) {
    for (let j = 1; j < N - 1; j++) {
      if (i * j >= N) {
        break
      }
      c++
    }
  }
  console.log(c + 1);
}


// 標準入力
main(require("fs").readFileSync("/dev/stdin", "utf8"))
