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 {
	  public static void main(String[] args) {

	    Scanner sc = new Scanner(System.in);
	    int n = sc.nextInt();
	    int h[] = new int[n];
	    int sum = 0;
	    int end = 0;
	    int w = 0;
	    for(int i=0; i<n; i++) {
	      h[i] = sc.nextInt();
	    }
	    while(end <= n){
	      end = 0;
	  	  for(int i=0; i<n; i++){
	        if(h[i] == 0){
	          end++;
	        }else{
	          w = i;
	          break;
	        }
	      }
	      if(end >= n){
	        break;
	      }
	      while(w < n){
	        if(h[w] <= 0){
	          break;
	        }else{
	          h[w]--;
	        }
	        w++;
	      }
	      sum++;
	    }
	    System.out.println(sum);
	  }
}