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) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		int h[] = new int[n];

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

		int count = 0;;
		while(true){
			//0じゃないところを探す
			int start = -1;
			for(int i = 0; i < n; i++){
				if(h[i] != 0){
					start = i;
					break;
				}
			}

			if(start < 0){
				break;
			}

			count++;

			for(int i = start; i < n; i++){
				if(h[i] == 0){
					break;
				}

				h[i]--;
			}
		}

		System.out.println(count);
	}
}
