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.Collections;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int N = Integer.parseInt(sc.next());
		ArrayList<Integer> nums=new ArrayList<Integer>(N);
		for(int i=0;i<N;i++) {
			nums.add(Integer.parseInt(sc.next()));
		}
		int ans=0;
		while(true)
		{
			
			int max=Collections.max(nums);
			if(max==0) {
				break;
			}
			int index=nums.indexOf(max);
			while(true) {
				nums.set(index, max-1);
				if(index==N-1) {
					break;
				}else if(nums.get(index)==nums.get(index+1)-1) {
					index+=1;
				}else {
					break;
				}
			}
			ans++;
			
		}
		System.out.println(ans);
		sc.close();
	}
	
}
