import sys

def input(): return sys.stdin.readline().rstrip()

def main():

    n = int(eval(input()))

    ans = 0

    for a in range(1,n):

        if a ** 2 >= n:

            break

        for b in range(a,n):

            if a * b >= n:

                break

            if a == b:

                ans += 1

            else:

                ans += 2

    print(ans)

        



if __name__=='__main__':

    main()
import sys

def input(): return sys.stdin.readline().rstrip()

def main():

    n = int(eval(input()))

    ans = 0

    for a in range(1,n):

        ans += -(-n//a) - 1

    print(ans)

        



if __name__=='__main__':

    main()
import sys


def input():
    return sys.stdin.readline().rstrip()


def main():
    n = int(eval(input()))
    ans = 0
    for a in range(1, n):
        if a**2 >= n:
            break
        for b in range(a, n):
            if a * b >= n:
                break
            if a == b:
                ans += 1
            else:
                ans += 2
    print(ans)


if __name__ == "__main__":
    main()

import sys


def input():
    return sys.stdin.readline().rstrip()


def main():
    n = int(eval(input()))
    ans = 0
    for a in range(1, n):
        ans += -(-n // a) - 1
    print(ans)


if __name__ == "__main__":
    main()

-        if a**2 >= n: -            break -        for b in range(a, n): -            if a * b >= n: -                break -            if a == b: -                ans += 1 -            else: -                ans += 2 +        ans += -(-n // a) - 1