This problem is a programming version of Problem 29 from projecteuler.net
Consider all integer combinations of for and :
If they are then placed in numerical order, with any repeats removed, we get the following sequence of 15 distinct terms:
How many distinct terms are in the sequence generated by for and ?
Input Format
Input contains an integer
Constraints
Output Format
Print the answer corresponding to the test case.
Sample Input
5
Sample Output
15