201121: [AtCoder]ARC112 B - -- - B

Memory Limit:1024 MB Time Limit:2 S
Judge Style:Text Compare Creator:
Submit:0 Solved:0

Description

Score : $400$ points

Problem Statement

Snuke has come to Seisu-ya (integer shop) with an integer $B$ in his hand. In Seiyu-ya, you can exchange your integer for another integer by paying money.

More specifically, you can use the following two services any number of times in any order:

  • Pay $1$ yen (the currency of Japan) to multiply your integer by $-1$.
  • Pay $2$ yen to subtract $1$ from your integer.

How many integers are there that Snuke can get for at most $C$ yen?

Constraints

  • $-10^{18}\le B \le 10^{18}$
  • $1\le C \le 10^{18}$
  • All values in input are integers.

Input

Input is given from Standard Input in the following format:

$B$ $C$

Output

Print the answer.


Sample Input 1

11 2

Sample Output 1

3

There are three numbers that Snuke can get: $-11$, $10$, and $11$, as follows:

  • by doing nothing, he can get $11$ for $0$ yen;
  • by multiplying $11$ by $-1$, he can get $-11$ for $1$ yen;
  • by subtracting $1$ from $11$, he can get $10$ for $2$ yen.

Sample Input 2

0 4

Sample Output 2

4

There are four numbers that Snuke can get: $-2$, $-1$, $0$, and $1$, as follows:

  • by doing nothing, he can get $0$ for $0$ yen;
  • by subtracting $1$ from $0$, he can get $-1$ for $2$ yen;
  • by subtracting $1$ from $0$ and then multiplying by $-1$, he can get $1$ for $3$ yen;
  • by subtracting $1$ from $0$ and then subtracting $1$ again, he can get $-2$ for $4$ yen.

Sample Input 3

112 20210213

Sample Output 3

20210436

Sample Input 4

-211 1000000000000000000

Sample Output 4

1000000000000000422

Input

题意翻译

初始有一个数 $B$, 然后他通过支付一定的钱来使这个数变为另外一个数,可以使用无数次的以下两个操作, 1.支付一元让这个数乘 $-1$, 2.支付两元使这个数减 $1$, 问在最多 $C$ 元的情况下可以得到多少个数?

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