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){
  	Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int array[] = new int[n];
    for(int i = 0; i < n; i++)
      array[i] = sc.nextInt();
    
    
    int count = 0;
    while(true){
      if(maxArray(array) == 0) break;
      int i = 0;
      while (i < n) {
        if (array[i] == 0) i++;
        else{
          count++;
          while (i < n && array[i] > 0){
            array[i]--;
            i++;
          }
        }
      }
    }
    System.out.println(count);
  }
  
  static int maxArray(int array[]){
    int max = 0;
    for(int i = 0; i < array.length; i++)
      if(max < array[i]) max = array[i];
    return max;
  }
}