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.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
public class Main {
    static int count = 0;
    static int heights[];
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        heights = new int[n];

        for(int i = 0; i < n; i++){
            heights[i] = sc.nextInt();
        }
        while(true){

            int sum = 0;
            for(int i = 0; i < heights.length; i++){
                sum += heights[i];
            }
            if(sum == 0){
                System.out.println(count);
                break;
            }
            reduceHeight(heights);
            //System.out.println(count + ":" + sum);

        }

    }

    private static void reduceHeight(int[] heights) {
        int min = 0;
        int max = heights.length;
        for(int i = 0; i < heights.length; i++){
            if(heights[i] > 0){
                min = i;
                break;
            }
        }

        for(int i = min; i < heights.length; i++){
            if(heights[i] == 0){
                max = i;
                break;
            }
        }
        for(int i = min; i < max; i++){
            heights[i] = heights[i] - 1;
        }

        count++;

    }


}