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.*;

/**
 * Main
 */
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int k[] = new int[N];
		Boolean allZero = false;
		int count = 0;

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

		while (!allZero) {
			allZero = true;
			int now = 0;
			int subcount = 0;
			while (now < N) {
				if (k[now] > 0) {
					k[now] -= 1;
					subcount++;
					allZero = false;
				} else if (k[now] <= 0 && subcount == 0) {
				} else {
					count++;
					subcount = 0;
				}
				now++;
			}
			if (subcount != 0) {
				count++;
			}
		}

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

