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[] h = new int[N];
    int count =0;
    for (int i =0; i<N; i++) {
      h[i] = sc.nextInt();
    }
    
    int a =0; int b=0;
    L:while (a<= N-1 && b<= N-1) {
      if (h[a] ==0) {
        a++;
        continue;
      }
      //aを決定
      b = a;
      while (b <= N-1) {
        if (h[b] !=0 && b != N -1) {
          b++;
          continue;
        } else {
          for (int i =a; i<=b; i++) {
            h[i]--;
            if (h[i] <0) {
              h[i] =0;
            }
          }
        }
        count++;
        continue L;
      }
    }
    System.out.println(count);
  }
}