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.*;
public class Main {
	static int count = 0;
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int num = sc.nextInt();
		int height[] = new int[num];
		for(int i = 0; i < num; i ++) {
			height[i] = sc.nextInt();
		}

		reduceHeight(height, 0, num);

		System.out.println(count);
	}

	public static void reduceHeight(int height[], int first, int last) {
		if(first != last) {
			int min = height[first];
			int index = first;
			for(int i = first; i < last; i ++) {
				if(height[i] < min) {
					min = height[i];
					index = i;
				}
			}
			boolean shouldContinue = false;
			for(int i = first; i < last; i ++) {
				height[i] -= min;
			}
			count += min;
			reduceHeight(height, first, index);
			reduceHeight(height, index + 1, last);
		}
	}
}