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.*;
import java.io.*;
public class Main{
    public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		PrintWriter ou = new PrintWriter(System.out);
		int n = Integer.parseInt(sc.next());
		int[] a = new int[n];
		for(int i = 0 ; i < n ; i++) a[i] = Integer.parseInt(sc.next());
		sc.close();
		boolean check = true;
		int yono = 0;
		while(check){
			int cou = 0;
			for(int i = 0 ; i < n ; i++){
				if(a[i] != 0){
					cou++;
					a[i]--;
				}else{
					if(cou != 0) yono++;
					cou = 0;
				}
			}
			if(cou != 0) yono++;
			boolean ch = true;
			for(int i = 0 ; i < n && ch ; i++){
				if(a[i] != 0) ch = false;
			}
			if(ch) check = false;
		}
		ou.print(yono + "\n");
		ou.flush();
    }
}