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 H = sc.nextInt();
		int[] h = new int[H + 1];
		int sum = 0;
		int c = 0;
		boolean t = false, z = false;

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

		while (sum > 0) {
			for (int i = 0; i < H; i++) {
				if (h[i] > 0) {
					h[i]--;
					sum--;
					t = true;
					z = true;
				} else {
					if (t) {
						c++;
						z = false;
					}
					t = false;
				}
			}
			if (z) {
				c++;
			}
			t = false;
		}

		System.out.println(c);

		sc.close();
	}
}
