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.Arrays;
import java.util.*;

public class Main{

         public static void main(String[] args) {

                Scanner scan = new Scanner(System.in);
                int N = scan.nextInt();
                int array[] = new int[N+1];
                int result=0;

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

                for(int i=N ; i > 0 ; i--){
                        if(array[i]<array[i-1]){
                                result+=array[i-1]-array[i];
                        }
                }

                System.out.println(result);
         }
}