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.Arrays;
import java.util.List;
import java.util.Scanner;
import java.util.stream.Collectors;

public class Main {

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int N = Integer.parseInt(s.nextLine());
        List<Integer> hs = Arrays.asList(s.nextLine().split(" ")).stream().map(Integer::parseInt)
                .collect(Collectors.toList());
        int count = 0;
        for (int i = 0; i < N;) {
            if (hs.get(i) == 0) {
                i++;
                continue;
            }
            for (int j = i; j < N; j++) {
                if (hs.get(j) == 0) {
                    break;
                }
                hs.set(j, hs.get(j) - 1);
                // System.out.println("ひいたあと" + hs);
            }
            count++;
        }
        System.out.println(count);
    }
}