Biluta de la RMI

Task

Luci has a small ball. This ball has an interesting property: it can move along the axis of integers! More precisely, it can only move within the interval $[-X, X]$. Luci noticed that the ball moves in the first minute by one position, in the second minute by two positions, $\dots$, in the $N$-th minute it moves $N$ positions. If it reaches one end of the interval $[-X, X]$, it changes direction and continues with the remaining number of positions.

If initially, the ball is at position $0$ and moves towards $X$, what position will it be in after $N$ minutes?

Input data

The first line will contain the numbers $X$ and $N$.

Output data

The first line will contain the position of the ball after $N$ minutes.

Constraints and clarifications

• $1 \leq X \leq 10^9$;
• $1 \leq N \leq 10^9$;

Example 1

biluta.in

4 3

biluta.out

2

Explicație

The ball moves as follows:

$0 \rightarrow 1 \rightarrow 3 \rightarrow 2$

Example 2

biluta.in

3 7

biluta.out

2

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