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 sc = new Scanner(System.in);
		int n = sc.nextInt();
		int h[] = new int[n];
		for (int i = 0; i < n; i++) {
			h[i] = sc.nextInt();
		}
		int ans = 0;

		for (int i = 0; i < n; i++) {
			while (h[i] > 1) {
				ans++;
				h[i]--;
				for (int i2 = i + 1; i2 < h.length; i2++) {
					if (h[i2] > 1) {
						h[i2]--;
					} else {
						break;
					}
				}
			}
		}

		boolean start = false;
		boolean zero = false;
		boolean none = true;
		for (int i = 0; i < n; i++) {
			if (h[i] != 0) {
				none = false;
				start = true;
				if (zero == true) {
					ans++;
					zero = false;
				}
			}
			if (h[i] == 0 && none == false) {
				zero = true;
			}
		}

		if (none == false)
			ans++;

		System.out.println(ans);

	}
}
