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;

class Main {

  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int n = scanner.nextInt();
    int[] l = new int[n];
    for (int i = 0; i < n; i++) {
      l[i] = scanner.nextInt();
    }
    scanner.close();
    int max = 0;
    for (int i = 0; i < n; i++) {
      if (max < l[i]) {
        max = l[i];
      }
    }
    if (n == 1) {
      System.out.println(max);
      return;
    }
    int count = 0;
    for (int i = max; i > 0; i--) {
      for (int j = 0; j < n - 1; j++) {
        if (l[j] == i) {
          if (l[j + 1] == i) {
            l[j]--;
          } else {
            l[j]--;
            count++;
          }
        }
      }
      if (l[n - 1] == i) {
        l[n - 1]--;
        count++;
      }
    }
    System.out.println(count);

  }

}
