problem

Given a sequence $ A $ of length $ N $. You can swap the $ i $ th and $ j $ th ($0 \ leq i, j \ leq N-1$) elements of a sequence up to $ M $ times.

Find the maximum value of $\ sum_ {i = 0} ^ {N -1} abs (A_i --i)$ in the sequence created by the operation.

output

Find the maximum value of $\ sum_ {i = 0} ^ {N --1} abs (A_i --i)$ in the sequence created by the operation. Also, output a line feed at the end.

Example

Input

5 2
0 3 2 1 4

Output

12

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