CF205B Little Elephant and Sorting

The Little Elephant loves sortings. He has an array $ a $ consisting of $ n $ integers. Let's number the array elements from 1 to $ n $ , then the $ i $ -th element will be denoted as $ a_{i} $ . The Little Elephant can make one move to choose an arbitrary pair of integers $ l $ and $ r $ $ (1

The first line contains a single integer $ n $ $ (1

In a single line print a single integer — the answer to the problem. Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64d specifier.

In the first sample the array is already sorted in the non-decreasing order, so the answer is $ 0 $ . In the second sample you need to perform two operations: first increase numbers from second to third (after that the array will be: \[3, 3, 2\]), and second increase only the last element (the array will be: \[3, 3, 3\]). In the third sample you should make at least 6 steps. The possible sequence of the operations is: (2; 3), (2; 3), (2; 3), (3; 3), (3; 3), (3; 3). After that the array converts to \[7, 7, 7, 47\].