100782: [AtCoder]ABC078 C - HSI

Problem Statement

Takahashi is now competing in a programming contest, but he received TLE in a problem where the answer is YES or NO.

When he checked the detailed status of the submission, there were $N$ test cases in the problem, and the code received TLE in $M$ of those cases.

Then, he rewrote the code to correctly solve each of those $M$ cases with $1/2$ probability in $1900$ milliseconds, and correctly solve each of the other $N-M$ cases without fail in $100$ milliseconds.

Now, he goes through the following process:

• Submit the code.
• Wait until the code finishes execution on all the cases.
• If the code fails to correctly solve some of the $M$ cases, submit it again.
• Repeat until the code correctly solve all the cases in one submission.

Let the expected value of the total execution time of the code be $X$ milliseconds. Print $X$ (as an integer).

Constraints

• All input values are integers.
• $1 \leq N \leq 100$
• $1 \leq M \leq {\rm min}(N, 5)$

Input

Input is given from Standard Input in the following format:

$N$ $M$

Output

Print $X$, the expected value of the total execution time of the code, as an integer. It can be proved that, under the constraints in this problem, $X$ is an integer not exceeding $10^9$.

Sample Input 1

1 1

Sample Output 1

3800

In this input, there is only one case. Takahashi will repeatedly submit the code that correctly solves this case with $1/2$ probability in $1900$ milliseconds.

The code will succeed in one attempt with $1/2$ probability, in two attempts with $1/4$ probability, and in three attempts with $1/8$ probability, and so on.

Thus, the answer is $1900 \times 1/2 + (2 \times 1900) \times 1/4 + (3 \times 1900) \times 1/8 + ... = 3800$.

Sample Input 2

10 2

Sample Output 2

18400

The code will take $1900$ milliseconds in each of the $2$ cases, and $100$ milliseconds in each of the $10-2=8$ cases. The probability of the code correctly solving all the cases is $1/2 \times 1/2 = 1/4$.

Sample Input 3

100 5

Sample Output 3

608000