Bitqoins

Miss M lives on the planet Bitaqulandia, where the most popular currency is the bitqoin. Recently, Miss M held a mini-competition for friends, where each winner receives exactly three bitqoins.

It is known that in Miss M's competition, the prize fund is $n$ bitqoins, $m$ people won, and each winner receives exactly three bitqoins.

Determine how many bitqoins will remain with Miss M if she gives three bitqoins to each winner. It is known that Miss M has enough bitqoins.

Input

The first line contains one integer $n$ ($3\le n\le 100$) — the number of bitqoins.

The second line contains one integer $m$ ($1\le m\le 100$) — the number of Miss M's friends who won in the competition.

It is guaranteed that Miss M will have enough bitqoins to distribute to her winning friends.

Output

Print a single integer — the number of bitqoins that will remain with Miss M after she distributes them to the winners.

Examples

Note

Miss M had two friends win, she will give three bitqoins to each of them. In total, she will give away six, so only four bitqoins will remain.