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) {
		final Scanner scanner = new Scanner(System.in);
		final int counter = scanner.nextInt();
		final int[] array = new int[counter];

		for (int i = 0; i < counter; i++) {
			array[i] = scanner.nextInt();
		}

		int result = 0;
		while (isLoopContinue(array)) {
			boolean bool = false;
			for (int i = 0; i < array.length; i++) {
				if (array[i] > 0) {
					bool = true;
					array[i]--;
				} else {
					if (bool) {
						bool = false;
						result++;
					}
				}
			}
			if (bool) {
				result++;
			}
		}
		System.out.println(result);
		scanner.close();
	}

	public static boolean isLoopContinue(final int[] array) {
		for (int i = 0; i < array.length; i++) {
			if (array[i] > 0) {
				return true;
			}
		}

		return false;
	}

}
