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.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;

public class Main{



	public static void main(String[] args) {

		Scanner scanner = new Scanner(System.in);

		int n        = Integer.parseInt(scanner.nextLine());
		String[] tmp = scanner.nextLine().split(" ");
		int[] list   = new int[n];
		int ans    	 = 0;

		for(int i = 0; i < n; i++) {
			list[i] = Integer.parseInt(tmp[i]);
		}


		for(int i = 0; i < n; i++) {

			int r   = i;
			int min = Integer.MAX_VALUE;

			while(list[i] != 0) {
				while(r < n && list[r] != 0) {

					min = Math.min(min, list[r]);
					r++;
				}

				for(int k = i; k < r; k++) {

					list[k] -= min;
				}

				ans += min;
				r = i;
			}

		}

		System.out.println(ans);
	}
}
