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 Scanner sc = new Scanner(System.in);
      static int n = sc.nextInt();
      static int[] h = new int[n];
    public static void main(String[] args){
      for(int i = 0;i < n;i++)h[i]=sc.nextInt();
      System.out.println(div(1,n));
    }
    public static int div(int x,int y){
      if(y==x) return h[x-1];
      if(y < x) return 0;
      int min = 10000000;
      for(int i = x;i <= y;i++){
      	min = Math.min(min,h[i-1]);
      }
      for(int i = x;i <= y;i++){
      	h[i-1]-=min;
      }
      for(int i = x;i <= y;i++){
      	if(h[i-1]==0)return div(x,i-1)+div(i+1,y)+min;
      }
      return 0;
    }
}