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 scanner = new Scanner(System.in);
        int N = scanner.nextInt();
        int[] h = new int[N];
        for (int i = 0; i < h.length; i++) {
            h[i] = scanner.nextInt();
        }
        int[] hc = new int[N];
        int ans = 0;
        while(true){
            int count = 0;
            boolean section = false;
            for (int i = 0; i < h.length; i++) {
                if(hc[i] < h[i]){
                    if(!section) count++;
                    section = true;
                    hc[i] ++;
                }else{
                    section = false;
                }
            }
            ans += count;
            if(count == 0) break;
        }
        System.out.println(ans);
    }
}