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 ≤ l ≤ r ≤ n) and increase a i by 1 for all i such that l ≤ i ≤ r . Help the Little Elephant find the minimum number of moves he needs to convert array a to an arbitrary array sorted in the non-decreasing order. Array a , consisting of n elements, is sorted in the non-decreasing order if for any i (1 ≤ i n) a i ≤ a i + 1 holds.
输入描述:
The first line contains a single integer n(1 ≤ n ≤ 105) — the size of array a. The next line contains n integers, separated by single spaces — array a(1 ≤ ai ≤ 109). The array elements are listed in the line in the order of their index's increasing.
输出描述:
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.
示例1
输入
3<br />1 2 3<br />3<br />3 2 1<br />4<br />7 4 1 47<br />
备注:
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].
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