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.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        try (Scanner sc = new Scanner(System.in);) {
            new Main().solve(sc);
        }
    }

    void solve(Scanner sc) {
        int n = sc.nextInt();
        int[] hs = new int[n + 2];
        hs[0] = hs[n + 1] = 0;
        for (int i = 1; i <= n; i++) {
            hs[i] = sc.nextInt();
        }

        boolean f = true;
        int ans = 0;
        while (f) {
            f = false;
            for (int i = 0; i <= n; i++) {
                if (hs[i] == 0) {
                    if (hs[i + 1] > 0) {
                        ans++;
                    }
                    continue;
                } 
                
                hs[i]--;
                f = true;
            }
        }
        System.out.println(ans);
    }
}
