#include <iostream>
using namespace std;

int main() {
	long long n, x, p = -1, ans = 0;
	cin >> n;
	for (long long i = 1; i <= n; i++) {
		cin >> x;
		if (p > x) {
			ans += p - x;
			x = p;
		}
		p = x;
	}
	cout << ans << endl;
	return 0;
}

### Prompt

Create a solution in Cpp for the following problem:

N persons are standing in a row. The height of the i-th person from the front is A_i.

We want to have each person stand on a stool of some heights - at least zero - so that the following condition is satisfied for every person:

Condition: Nobody in front of the person is taller than the person. Here, the height of a person includes the stool.

Find the minimum total height of the stools needed to meet this goal.

Constraints

* 1 \leq N \leq 2\times 10^5
* 1 \leq A_i \leq 10^9
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N
A_1 \ldots A_N


Output

Print the minimum total height of the stools needed to meet the goal.

Examples

Input

5
2 1 5 4 3


Output

4


Input

5
3 3 3 3 3


Output

0

### Response

```cpp
#include <iostream>
using namespace std;

int main() {
	long long n, x, p = -1, ans = 0;
	cin >> n;
	for (long long i = 1; i <= n; i++) {
		cin >> x;
		if (p > x) {
			ans += p - x;
			x = p;
		}
		p = x;
	}
	cout << ans << endl;
	return 0;
}

```