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[] s = new int[n];
        int[] h = new int[n];
        for (int i = 0; i < n; i++) h[i] = sc.nextInt();

        int cnt = 0;
        boolean flag = false;

        while (true) {
            flag = false;
            for (int i = 0; i < n; i++) {
                if (s[i] != h[i]) {
                    s[i] += 1;
                    flag = true;
                } else if (s[i] == h[i] && flag) {
                    cnt += 1;
                    flag = false;

                }
            }
            if (flag) cnt += 1;
            if (Arrays.equals(s, h)) break;
        }
        System.out.println(cnt);
    }
}
