In a flower bed, there are N flowers, numbered 1,2,......,N. Initially, the heights of all flowers are 0. You are given a sequence h=\\{h_1,h_2,h_3,......\\} as input. You would like to change the height of Flower k to h_k for all k (1 \leq k \leq N), by repeating the following "watering" operation:

* Specify integers l and r. Increase the height of Flower x by 1 for all x such that l \leq x \leq r.



Find the minimum number of watering operations required to satisfy the condition.

Constraints

* 1 \leq N \leq 100
* 0 \leq h_i \leq 100
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N
h_1 h_2 h_3 ...... h_N


Output

Print the minimum number of watering operations required to satisfy the condition.

Examples

Input

4
1 2 2 1


Output

2


Input

5
3 1 2 3 1


Output

5


Input

8
4 23 75 0 23 96 50 100


Output

221
import java.util.Scanner;
import java.util.Stack;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();

		int answer = 0;
		Stack<Integer> st = new Stack<>();
		for (int i = 0; i < n; i++) {
			int x = sc.nextInt();
			if (st.isEmpty() || st.peek() <= x) st.push(x);
			else {
				int prev = st.pop();
				while (!st.isEmpty() && st.peek() > x) st.pop();
				answer += prev - x;
				st.push(x);
			}
		}

		if (!st.isEmpty()) answer += st.peek();
		System.out.println(answer);
	}

}
