Stepan and pairs

Very easy

Execution time limit is 1 second

Runtime memory usage limit is 128 megabytes

Stepan is interested in the greatest common divisor of a pair of numbers, specifically $GC D (x, y)$ . Given an integer $n$ , Stepan wants to know how many pairs of integers $(i, j)$ exist such that $1 \leq i, j \leq n$ and the equation $i = GC D (i, j)$ is satisfied.

Input

One integer $n (1 \leq n \leq 1 0^{6})$ .

Output

Print the number of required pairs.

Examples

Input #1

Answer #1

Input #2

Answer #2

Input #3

Answer #3

Submissions 3K

Acceptance rate 55%