Problem Statement

Given is a positive integer $N$. Find the value $\\displaystyle\\sum_{i=1}^N \\left\[ \\frac{N}{i} \\right\]$.

Here, for a real number $x$, \[x\] denotes the largest integer not exceeding $x$.

Constraints

• $1 \\leq N \\leq 10^{12}$
• $N$ is an integer.

Input

Input is given from Standard Input in the following format:

$N$

Output

Print the answer.

Sample Input 1

3

Sample Output 1

5

We have $\\left\[ \\frac{3}{1} \\right\]+\\left\[ \\frac{3}{2} \\right\]+\\left\[ \\frac{3}{3} \\right\]=3+1+1=5$.

Sample Input 2

10000000000

Sample Output 2

231802823220

Note that the input and output may not fit into a $32$-bit integer type.