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.io.*;

/*
   AtCoder contest code
   coder : yoichidon
 */
import java.util.*;
import java.io.*;

public class Main {
    public static int positiveRangeCount(int[] h){
        int ans=0;
        for(int n=0; n<h.length; n++){
            if(h[n]>0 && (n==0 || h[n-1]<=0)) ans++;
        }
        return ans;
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] h = new int[N];
        for(int n=0; n<N; n++) h[n]=sc.nextInt();

        int water = 0;
        while(positiveRangeCount(h) >0){
            water += positiveRangeCount(h);
            for(int n=0; n<N; n++) h[n]--;
        }

        System.out.println(water);

    }
}
