Sum Even Fibonacci Terms

Begin the sequence with 1 and 2. Each following term is the sum of the previous two. Include only even-valued terms no greater than limit, then add them.

Implement even_fibonacci_sum(limit).

Input

limit: The largest term value that may be included.

Output

Return the sum, or 0 if there are no eligible terms.

Vincoli

0 ≤ limit ≤ 10¹⁵. The result fits a signed 64-bit integer.

Esempi

Input:
limit = 50

Output atteso:
expected = 44

Input:
long long limit = 50;

Output atteso:
long long expected = 44;

Input:
long limit = 50;

Output atteso:
long expected = 44;

Input:
limit = 1

Output atteso:
expected = 0

Input:
long long limit = 1;

Output atteso:
long long expected = 0;

Input:
long limit = 1;

Output atteso:
long expected = 0;

Riferimenti

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• #2 Even Fibonacci Numbers