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;

public class Main {

	public static void main(String[] args) {
		
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int[] h = new int[n];
		for (int i = 0; i < n; i++)
			h[i] = in.nextInt();
		
		System.out.println(water(h, 0, n - 1));		

	}
	
	public static int water(int[] h, int left, int right){

		if (right < left)
			return 0;
		else {
			int min = h[left];
			for (int i = left; i <= right; i++) 
				min = Math.min(min,	h[i]);
			for (int i = left; i <= right; i++)
				h[i] -= min;
			for (int i = left; i <= right; i++) {
				if (h[i] == 0)
					return min + water(h, left, i - 1) + water(h, i + 1, right);
			}
			
		}
		return 0;

	}

}