# Problem B

Fleytitala

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Friðrik is killing time by skipping stones. He’s getting so good at it that he can decide how often the stone will bounce.

Friðrik starts by throwing the stone $d$ meters. After each bounce the distance the stone travels is cut in half. How many meters does the stone travel in total?

## Input

The input consists of two lines. The first line contains one integer $0 \leq d \leq 10^6$, the distance that the stone will travel before bouncing. The second line contains one integer $0 \leq k \leq 10^{18}$, the number of bounces.

## Output

Print a single line with a floating point number, the total distance that the stone travels.

The output is considered correct if the number has a relative or absolute error of at most $10^{-5}$ from the correct answer. This means it doesn’t matter how many significant digits the answer contains as long as it’s accurate enough.

## Scoring

Group |
Points |
Constraints |

1 |
25 |
$0 \leq k \leq 10$ |

2 |
50 |
$0 \leq k \leq 1\, 000$ |

3 |
25 |
No further constraints |

Sample Input 1 | Sample Output 1 |
---|---|

1 1 |
1.5 |

Sample Input 2 | Sample Output 2 |
---|---|

12 4 |
23.25 |

Sample Input 3 | Sample Output 3 |
---|---|

0 10 |
0.0 |