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 scan = new Scanner(System.in);
		int flowerNum = scan.nextInt();						// 花の総本数
		int[] flowerHeightList = new int[flowerNum]; 			// 花の高さを入れる配列
		int count = 0; 											// 水やり回数

		/* データ入力 */
		for (int i = 0; i < flowerNum; i++) {
			flowerHeightList[i] = scan.nextInt();
		}

		int tmp = 0;
		int head = 0;

		while(head < flowerNum) {
			// 現在の先頭要素が0だった場合、先頭を変更
			if(flowerHeightList[head] == 0) {
				tmp = ++head;
				continue;
			}
			// 水やりの範囲を決定する
			for(int tail = head; tail < flowerNum; tail++) {
				if(flowerHeightList[tail] == 0) {
					head = tmp;
					break;
				}
				flowerHeightList[tail]--;
			}
			count++;
		}

		System.out.println(count);
		scan.close();
	}

}
