Triangles from Matches
Medium
Execution time limit is 1 second
Runtime memory usage limit is 122.174 megabytes
Professor Samodelkin decided to show his mental abilities again from problem "Match model". He started to construct the triangles with matches.
What is the minimal number of matches needs Samodelkin to construct n triangles with side of one match.
Input
One number n (n < 2*10^9).
Output
Print the number of used matches.
Examples
Input #1
Answer #1
Submissions 7K
Acceptance rate 13%