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2017-12-16 14:00 CET

Local Contest

End

2017-12-23 14:00 CET
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Problem D
R2

The number $S$ is called the mean of two numbers $R_1$ and $R_2$ if $S$ is equal to $(R_1+R_2)/2$. Mirko’s birthday present for Slavko was two integers $R_1$ and $R_2$. Slavko promptly calculated their mean which also happened to be an integer but then lost $R_2$! Help Slavko restore $R_2$.

Input

The first and only line of input contains two integers $R_1$ and $S$, both between $-1\, 000$ and $1\, 000$.

Output

Output $R_2$ on a single line.

Sample Input 1 Sample Output 1
11 15
19
Sample Input 2 Sample Output 2
4 3
2