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.*;

class Main{
	static int[] nums;

	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int num = sc.nextInt();
		nums = new int[num];
		for(int i = 0; i < num; i++)nums[i] = sc.nextInt();

		int ans = divZero(0, num-1);
		System.out.println(ans);
	}

	static public int divZero(int start, int end){
		if(start == end)return nums[end];
		if(start > end)return 0;

		for(int i = start; i <= end; i++){
			if(nums[i] == 0)return divZero(start, i-1) + divZero(i+1, end);
		}

		int min = 101;
		for(int i = start; i <= end; i++)if(nums[i] < min)min = nums[i];
		for(int i = start; i <= end; i++)nums[i] -= min;
		return min + divZero(start, end);
	}
}