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
# inp.readline()
# int(inp.readline())
# out.write()
# raw_input()
# map(int,raw_input().split())
# map(int,inp.readline().split())
# for _ in xrange(input()):
# print "Case #"+str(_+1)+": "+ 
if __name__ == "__main__":
    from sys import stdin as inp, stdout as out,setrecursionlimit as srl
    from collections import Counter,defaultdict,deque
    from heapq import *
    for _ in xrange(1):
        n=input()
        t=int(pow(n,0.5))+1
        c=Counter()
        for i in xrange(1,t+1):
          for j in xrange(i*i,n+1,i):
            c[j]+=1
        print 2*sum(c[i] for i in xrange(1,n))-int(pow(n-1,0.5))