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.*;
public class Main {
	public static void main(String[] args)
	{
		//変数
		//int count=0;
		//boolean sw=false;
		int answer=0;
		//String answer="NO";
		//List<Integer> h=new ArrayList<Integer>();
		//int af=Integer.MAX_VALUE;
		int N=0;
		int v=0;
		int e=0;
		//int t[]=new int[(int)Math.pow(10,5)];
		//入力
		Scanner sc = new Scanner(System.in);
		N=sc.nextInt();
		int h[]=new int[N];
		for(int i=0;i<N;i++)
		{
			h[i]=sc.nextInt();
		}
		//int a=sc.nextInt();
		//String S=sc.next();
		//int [][] cost =new int[N-1][2];
		
		//処理
		for(int i=0;i<N;i++)
		{
			v+=h[i];
		}
		for(int i=1;i<N;i++)
		{
			e+=Math.min(h[i-1],h[i]);
		}
		answer=v-e;
		// 出力
		System.out.println(answer);
	}
}