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.*;
import java.awt.*;
import java.awt.geom.*;
import static java.lang.System.*;
import static java.lang.Math.*;
public class Main {
    public static void main(String[] $) {
        Scanner sc = new Scanner(in);
        int n=sc.nextInt();
        int[] h=new int[n+1];
        for (int i = 0; i < n; i++) {
            h[i]=sc.nextInt();
        }
        h[n]=0;
        long ans=0;
        int sum=1;
        while (sum>0) {
            sum=0;
            int c=0;
            for (int i = 0; i < n; i++) {
                if(h[i]>0){
                    h[i]--;
                    if(h[i+1]==0)c++;
                }
                sum+=h[i];
            }
            ans+=c;
        }
        out.println(ans);
    }
}