Cut a segment with length \textbf{L} on the most quantity of parts the lengths of which are natural numbers, that from them it is not impossible to make a single triangle. \textbf{Input } The length of the segment \textbf{L}. \textbf{4} <= \textbf{L} <= \textbf{2000000000}. \textbf{Output} The required number of parts.