#!/usr/bin/env python3

import sys

import numpy as np

import numba



input = sys.stdin.readline





def I():

    return int(eval(input()))





# @njit((i8[:],), cache=True)

@numba.jit

def main(n):

    table = np.zeros(n, np.int64)



    for i in range(1, n):

        table[::i] += 1



    ans = 0

    for n in table[1:]:

        q, r = divmod(n, 2)

        ans += q * 2 + 1 * r



    return ans





N = I()



print((int(main(N))))

#!/usr/bin/env python3

import sys

import numpy as np

import numba

from numba import njit, b1, i4, i8, f8



input = sys.stdin.readline





def I():

    return int(eval(input()))





@njit((i8,), cache=True)

def main(n):

    table = np.zeros(n, np.int64)



    for i in range(1, n):

        table[::i] += 1



    ans = 0

    for n in table[1:]:

        q, r = divmod(n, 2)

        ans += q * 2 + 1 * r



    return ans





N = I()



print((int(main(N))))

#!/usr/bin/env python3
import sys
import numpy as np
import numba

input = sys.stdin.readline


def I():
    return int(eval(input()))


# @njit((i8[:],), cache=True)
@numba.jit
def main(n):
    table = np.zeros(n, np.int64)
    for i in range(1, n):
        table[::i] += 1
    ans = 0
    for n in table[1:]:
        q, r = divmod(n, 2)
        ans += q * 2 + 1 * r
    return ans


N = I()
print((int(main(N))))

#!/usr/bin/env python3
import sys
import numpy as np
import numba
from numba import njit, b1, i4, i8, f8

input = sys.stdin.readline


def I():
    return int(eval(input()))


@njit((i8,), cache=True)
def main(n):
    table = np.zeros(n, np.int64)
    for i in range(1, n):
        table[::i] += 1
    ans = 0
    for n in table[1:]:
        q, r = divmod(n, 2)
        ans += q * 2 + 1 * r
    return ans


N = I()
print((int(main(N))))

+from numba import njit, b1, i4, i8, f8 -# @njit((i8[:],), cache=True) -@numba.jit +@njit((i8,), cache=True)