Competitions

# 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.

#### Input

The number of hexagons n (1n45) in the upper row. The lower row contains 1 hexagon less.

#### Output

Print the number of ways to get from the first cell of the top row to the last cell of the same row.

Time limit 1 second
Memory limit 128 MiB
Input example #1
1

Output example #1
1

Input example #3
3

Output example #3
2