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 in = new Scanner(System.in);
		int N = in.nextInt();
		int[] h = new int[N];
		for (int i = 0; i < N; i++) {
			h[i] = in.nextInt();
		}
		int ans = 0;
		while (true) {
			int left = -1;
			for (int i = 0; i < N; i++) {
				if (h[i] != 0) {
					left = i;
					break;
				}
			}
			if (left == -1) {
				break;
			}
			int right = left;
			while (right + 1 < N && h[right] <= h[right + 1]) {
				right++;
			}
			for (int j = left; j <= right; j++) {
				h[j] -= 1;
			}
			ans += 1;
		}
		System.out.println(ans);
		in.close();
	}
}