Modified Fibonacci Sequence

You are given a modified Fibonacci sequence defined as follows:

The first three terms are given as:

• a(1) = 0
• a(2) = 1
• a(3) = 1

For all n > 3, the n-th term is defined by the recurrence relation:

$$a(n)=a(n-3)+a(n-2)+a(n-1)$$

Your task is to compute the n-th term of this sequence.

inputFormat

The input consists of a single integer n (n ≥ 1) provided via standard input.

outputFormat

Output the n-th term of the modified Fibonacci sequence on a single line to standard output.

## sample

1

0

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