Given an integer N. Consider all the possible permutations of all integers from to . Calculate the value of for each permutation :
Determine the sum of all for all possible permutations.
Input format
Output format
For each test case, print a single line containing the answer.
Constraints
There are 2 possible permutations for N = 2 : p = [1, 2] and p = [2, 1].
For first permutation X = (2 - 1) + (2 - 2) = 1.
For second permutation X = (2 - 2) + (2 - 1) = 1.
So sum of X over 2 possible permutations = 2.