FLARIT - Floor Arithmetics

Given N, calculate

\sum_{i=1}^N \left \lfloor \frac{N}{i} \right \rfloor

i.e. the sum of all N divided by i, rounded down, for all i from 1 to N.

Input

A positive integer N (N ≤ 10^12).

Output

The sum of all N divided by i, rounded down, for all from 1 to N.

Example

Input:
4

Output:
8
Input:
10

Output:
27
Input:
32

Output:
119

Added by:Emerson Leonardo Lucena
Date:2017-12-13
Time limit:1s
Source limit:10000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All

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