"We can rebuild him. We have the technology. We can make him better than he was. Better, stronger, faster."

Frosty the Snowman's power is limited to the winter months. Therefore, he cannot torment the students at Martingrove for a lot of the school year. Charles wishes to change this. If he uses the super mega snowball to summon Frosty at the unholy mattress behind the gas station he will become invulnerable, letting him reign terror for the entire school year.

The super mega snowball has some special properties. It starts at $1$ kilogram, and for every $1$ metre it rolls it will gain $1$ kilogram. Charles needs to roll the snowball $N$ metres to the desired location, and he can roll a snowball of a maximum weight of $W$ kilograms.

Can Charles summon Frosty with the super mega snowball?

Constraints

$1\le N,W\le 100$

Input Specification

The only line will contain integers $N$ and $W$ separated by a space.

Output Specification

Output possible if Charles can summon Frosty. Otherwise output impossible if he cannot.

Sample Input 1

5 5

Sample Output 1

impossible

Sample Input 2

5 6

Sample Output 2

possible