A * B + C

Positive integer $n$ is given. How many tuples $(A,B,C)$ of positive integers satisfy $A\cdot B+C=n$?

Input

One positive integer $n(2\le n\le 10^8)$.

Output

Print the required number of tuples.

Examples

Note

For $n=3$ there are exactly three triplets:

• $(1,1,2)$, since $1\cdot 1+2=3$;

• $(1,2,1)$, since $1\cdot 2+1=3$;

• $(2,1,1)$, since $2\cdot 1+1=3$.