Buy the water

The cost of a bottle of water (including the cost of the empty bottle) is $1$ dollar $20$ cents. The cost of the empty bottle is $20$ cents.

How many bottles of water is it possible to drink for $n$ dollars, if you can recycle bottles for cash and buy new bottles of water for this cach.

Input

Positive integer $n$ $(1\le n\le 1000)$.

Output

Number of bottles of water that you can drink for $n$ dollars.

Examples