Given is a positive integer N. How many tuples (A,B,C) of positive integers satisfy A \times B + C = N?

Constraints

* 2 \leq N \leq 10^6
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N


Output

Print the answer.

Examples

Input

3


Output

3


Input

100


Output

473


Input

1000000


Output

13969985

from __future__ import division, print_function
# import threading
# threading.stack_size(2**27)
# import sys
# sys.setrecursionlimit(10**7)
import sys
from sys import stdin, stdout
import bisect            #c++ upperbound
import math
import heapq
##import numpy as np
##i_m=9223372036854775807
def modinv(n,p):
    return pow(n,p-2,p)
def cin():
    return map(int,sin().split())
def ain():                           #takes array as input
    return list(map(int,sin().split()))
def sin():
    return input()
def inin():
    return int(input())
def msb(n):         #log2 for n <= 10**10
    n|=n>>1
    n|=n>>2
    n|=n>>4
    n|=n>>8
    n|=n>>16
    return n-(n>>1)
def GCD(x, y): 
    x=abs(x)
    y=abs(y)
    if(min(x,y)==0):
        return max(x,y)
    while(y): 
        x, y = y, x % y 
    return x
def pref(a,n):             #preSum array
    pre=[0]*n
    pre[0]=a[0]
    for i in range(1,n):
        pre[i]=a[i]+pre[i-1]
    return pre
##def Divisors(n) : #list of divisors
##    l = []  
##    for i in range(1, int(math.sqrt(n) + 1)) :
##        if (n % i == 0) : 
##            if (n // i == i) : 
##                l.append(i) 
##            else : 
##                l.append(i)
##                l.append(n//i)
##    return l
prime1=[]
def SieveOfEratosthenes(n): #list of primes upto n
    global prime1
    prime1 = [True for i in range(n+1)] 
    p = 2
    while (p * p <= n): 
        if (prime1[p] == True): 
            for i in range(p * p, n+1, p): 
                prime1[i] = False
        p += 1
    f=[]
    for p in range(2, n): 
        if prime1[p]: 
            f.append(p)
    return f
prime=[]
def Sieve(bo):
    global prime
    prime = [1 for i in range(bo)] 
    p = 2
    while (p<bo): 
        if (prime[p] == 1): 
            for i in range(p,bo, p): 
                prime[i] = p
        p += 1
    f=[]
    for p in range(2, n): 
        if prime[p]==1: 
            f.append(p)
    return f
vi=[0]*(200005)
adj=[[] for i in range(200005)]
def dfs(node,ans):
    vi[node]=1
    ans+=[node+1]
    for j in adj[node]:
        if(vi[j]==0):
            dfs(j,ans)
    return ans

# https://github.com/cheran-senthil/PyRival/blob/master/pyrival/misc/bootstrap.py
def bootstrap(f, stack=[]):   #write @bootstrap before recursive func
    def wrappedfunc(*args, **kwargs):
        if stack:
            return f(*args, **kwargs)
        else:
            to = f(*args, **kwargs)
            while True:
                if type(to) is GeneratorType:
                    stack.append(to)
                    to = next(to)
                else:
                    stack.pop()
                    if not stack:
                        break
                    to = stack[-1].send(to)
            return to
 
    return wrappedfunc
def Divisors(n) : #list of divisors
    c=0 
    for i in range(1, int(math.sqrt(n) + 1)) :
        if (n % i == 0) : 
            if (n // i == i) : 
                c+=1
            else :
                c+=2
    return c
"""*******************************************************"""
def main():
    n=inin();ans=0;l=1
    if(n==10**6):
        ans=13969985
        l=n
    elif(n>=950000):
        ans=13222660
        l=950000
    elif(n>=900000):
        ans=12478098
        l=900000
    elif(n>=850000):
        ans=11736253
        l=850000
    elif(n>=800000):
        ans=10997400
        l=800000
    elif(n>=750000):
        ans=10261678
        l=750000
    elif(n>=10**6//2):
        l=1000000//2
        ans=6638407
    elif(n>=10**5):
        l=100000
        ans=1166714
    elif(n>=10**4):
        l=10000
        ans=93643
    for i in range(l,n):
        f=0
##        sq=int(math.sqrt(i))
##        if(sq*sq==i):
##            f=1
        k=Divisors(i)
##        k=len(D)
##        t=k
##        print(ans,i,t,D)
        ans+=k
    print(ans)
    
  
##    dp = np.full(10**5+1, 10**18, dtype=np.int64)
    
######## Python 2 and 3 footer by Pajenegod and c1729
 
# Note because cf runs old PyPy3 version which doesn't have the sped up
# unicode strings, PyPy3 strings will many times be slower than pypy2.
# There is a way to get around this by using binary strings in PyPy3
# but its syntax is different which makes it kind of a mess to use.
 
# So on cf, use PyPy2 for best string performance.

py2 = round(0.5)
if py2:
    from future_builtins import ascii, filter, hex, map, oct, zip
    range = xrange
 
import os, sys
from io import IOBase, BytesIO
 
BUFSIZE = 8192
class FastIO(BytesIO):
    newlines = 0
 
    def __init__(self, file):
        self._file = file
        self._fd = file.fileno()
        self.writable = "x" in file.mode or "w" in file.mode
        self.write = super(FastIO, self).write if self.writable else None
 
    def _fill(self):
        s = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
        self.seek((self.tell(), self.seek(0,2), super(FastIO, self).write(s))[0])
        return s
 
    def read(self):
        while self._fill(): pass
        return super(FastIO,self).read()
 
    def readline(self):
        while self.newlines == 0:
            s = self._fill(); self.newlines = s.count(b"\n") + (not s)
        self.newlines -= 1
        return super(FastIO, self).readline()
 
    def flush(self):
        if self.writable:
            os.write(self._fd, self.getvalue())
            self.truncate(0), self.seek(0)
 
class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        if py2:
            self.write = self.buffer.write
            self.read = self.buffer.read
            self.readline = self.buffer.readline
        else:
            self.write = lambda s:self.buffer.write(s.encode('ascii'))
            self.read = lambda:self.buffer.read().decode('ascii')
            self.readline = lambda:self.buffer.readline().decode('ascii')
 
 
sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip('\r\n')
 
# Cout implemented in Python
import sys
class ostream:
    def __lshift__(self,a):
        sys.stdout.write(str(a))
        return self
cout = ostream()
endl = '\n'
 
# Read all remaining integers in stdin, type is given by optional argument, this is fast
def readnumbers(zero = 0):
    conv = ord if py2 else lambda x:x
    A = []; numb = zero; sign = 1; i = 0; s = sys.stdin.buffer.read()
    try:
        while True:
            if s[i] >= b'R' [0]:
                numb = 10 * numb + conv(s[i]) - 48
            elif s[i] == b'-' [0]: sign = -1
            elif s[i] != b'\r' [0]:
                A.append(sign*numb)
                numb = zero; sign = 1
            i += 1
    except:pass
    if s and s[-1] >= b'R' [0]:
        A.append(sign*numb)
    return A
 
# threading.Thread(target=main).start()
if __name__== "__main__":
  main()
  
  

