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.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int tmp = sc.nextInt();
		int tmp2 = tmp;
		List<Integer> list = new ArrayList<>();
		if(N == 1) {
			list.add(tmp);
		}
		boolean up = false, down = false;
		for(int i = 1; i < N; i++) {
			tmp2 = sc.nextInt();
			if(tmp2 > tmp) {
				if(!up) {
					list.add(tmp);
				}
				up = true;
				down = false;
			} else if(tmp2 < tmp) {
				if(!down) {
					list.add(tmp);
				}
				down = true;
				up = false;
			}
			if(i == N - 1) {
				list.add(tmp2);
			}
			tmp = tmp2;
		}
		int ans = list.get(0);
		int high = list.get(0);
		list.remove(0);
		while(!list.isEmpty()) {
			if(high < list.get(0)) {
				ans += list.get(0) - high;
			}
			high = list.get(0);
			list.remove(0);
		}
		System.out.println(ans);
	}

}
