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.*;
class Main {
  public static void main (String[] args) throws Exception {
    
    Scanner sc = new Scanner(System.in);
    
    int n = sc.nextInt();
    int [] f = new int [n];
    
    int ans=0;
    
    for(int i=0; i<n; i++){
      f[i]=sc.nextInt();
     }
     
     boolean flag = false;
     int count =0;
     int d=0;
      
     while(count<n){
       if(d==n){
          d=0;
          if(flag==true)ans++;
          flag=false;
          }
       if(f[d]!=0){
         count=0;
         flag = true;
         f[d]--;
         }else{
           if(flag==true)ans++;
           flag=false;
           count++;
          }
        d++;
          
              //System.out.println(f[0]+" "+f[1]+" "+f[2]+" "+f[3]+" "+f[4]+" ans "+ans);
          
       }
       
      System.out.println(ans);

  }
  
}