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
#約数の個数の和（１~N）約数そのものを求めないので「速い」
def yakusu_num(N):
    ans =0
    for i in range(1,N+1):
        ans +=N//i #項数
    return ans


# 初期入力
import sys
input = sys.stdin.readline  #文字列では使わない

N = int(input())
ans =yakusu_num(N-1)

print(ans)