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
import itertools
import collections

N = int(input())

def prime_factor_table(n):
    table = [0] * (n + 1)
    
    for i in xrange(2, n + 1):
        if table[i] == 0:
            for j in xrange(i + i, n + 1, i):
                table[j] = i
    
    return table

def prime_factor(n, prime_factor_table):
    prime_count = collections.Counter()
    
    while prime_factor_table[n] != 0:
        prime_count[prime_factor_table[n]] += 1
        n /= prime_factor_table[n]
    prime_count[n] += 1
    
    return prime_count

t = prime_factor_table(N)

ans = 0
for c in range(1,N-1):
  ab = N-c
  f = prime_factor(ab,t)
  v = f.values()
  tmp = 1
  for i in range(len(f)):
    tmp *= v[i]+1
  ans += tmp
  
print(ans+1)