- Time limit: 1.00 s
- Memory limit: 512 MB
On each turn, a robot moves one step left, right, up or down, but not outside the board. It randomly chooses a direction among those where it can move.
Your task is to calculate the expected number of empty squares after $k$ turns.
The only input line has an integer $k$.
Print the expected number of empty squares rounded to six decimal places.
- $1 \le k \le 100$