Sum of Fibonacci Numbers Up to n

Given an integer n, calculate the sum of all Fibonacci numbers that are less than or equal to n. The Fibonacci sequence is defined as follows:

\(F_0 = 0,\; F_1 = 1,\; F_n = F_{n-1} + F_{n-2}\) for \(n \ge 2\).

If n is zero or negative, the output should be 0.

For example, when n = 10, the Fibonacci numbers up to 10 are: 0, 1, 1, 2, 3, 5, 8, and the sum is 20.

Your program should read the input from standard input (stdin) and output the result to standard output (stdout).

inputFormat

The input consists of a single integer n provided via standard input.

Example:

10

outputFormat

Output a single integer which is the sum of all Fibonacci numbers that do not exceed n.

Example:

20

## sample

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