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 {
	static int N;
	static int[] flowers;
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		 N = sc.nextInt();
		 flowers = new int[N];

		 for(int i = 0 ; i < N ; i++){
			 flowers[i] = sc.nextInt();
			 }
		 sc.close();

		 int ans = 0;
		 int cur = 0;

			 for(int k = 0 ; k < N ; k++){
				if(flowers[k]>cur){
					ans += flowers[k] - cur;
				 }
			cur = flowers[k];
			 }
		 System.out.println(ans);


	}
}
