Problem:
Score : 300 points

Problem Statement

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.

Sample Input 1

4
1 2 2 1

Sample Output 1

2

The minimum number of watering operations required is 2.
One way to achieve it is:

Perform the operation with (l,r)=(1,3).

Perform the operation with (l,r)=(2,4).

Sample Input 2

5
3 1 2 3 1

Sample Output 2

5

Sample Input 3

8
4 23 75 0 23 96 50 100

Sample Output 3

221

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;

public class Main {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] as = new int[n];
        for (int i = 0; i < n; i++) {
            as[i] = sc.nextInt();
        }

        int cnt = 0;
        while (true) {
            int nax = 0;
            for (int i = 0; i < n; i++) {
                nax = Math.max(nax, as[i]);
            }
            // System.err.println(nax);
            if (nax == 0) break;
            int stat = 0;
            for (int i = 0; i < n; i++) {
                if (stat <= 1 && as[i] == nax) {
                    as[i]--;
                    stat =  1;
                } else if (stat == 1 && as[i] != nax) {
                    break;
                }
            }
            cnt++;
        }
        System.out.println(cnt);
    }
}