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.io.InputStream;
import java.io.PrintStream;
import java.util.Scanner;

public class Main {
	InputStream in = System.in;
	PrintStream out = System.out;

	int next(int[] h, int idx) {
		for (int i = idx; i < h.length; i++) {
			if (h[i] != 0) {
				return i;
			}
		}
		return -1;
	}

	public void _main(String[] args) {
		Scanner sc = new Scanner(in);

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

		int ans = 0;
		int idx = 0;
		while (true) {
			idx = next(h, idx);
			if (idx == -1) {
				break;
			}

			while (h[idx] > 0) {
				ans++;
				for (int i = idx; i < n && h[i] > 0; i++) {
					h[i]--;
				}
			}
		}

		out.println(ans);

		sc.close();

	}

	public static void main(String[] args) {
		new Main()._main(args);
	}

}
