Problems
Honeycomb
Honeycomb
The bee can go in honeycomb as shown in the figure --- with moves $1$ and $2$ from upper row and with move $3$ from the lower.
\includegraphics{https://static.e-olymp.com/content/44/444be65c2ca0ec12efbd13c7c7cde85f292e12a6.jpg}
\InputFile
The number of hexagons $n~(1 \le n \le 45)$ in the upper row. The lower row contains $1$ hexagon less.
\OutputFile
Print the number of ways to get from the first cell of the top row to the last cell of the same row.
Input example #1
1
Output example #1
1
Input example #3
3
Output example #3
2