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.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        List<Integer> list=new ArrayList<>();
        List<Integer> hana=new ArrayList<>();
        int count=0;
        
        for(int i=0;i<a;i++){
            int h=sc.nextInt();
            list.add(h);
            hana.add(0);
        }
        
        for(int i=0;i<a;i++){
                for(int t=0;t<list.get(i);t++){
                    if(hana.get(i)<list.get(i)){
                        hana.set(i, hana.get(i)+1);
                        if(i+1==list.size()){

                        }else{
                            if(hana.get(i+1)<list.get(i+1)){
                                for(int x=i+1;x<a;x++){
                                    if(hana.get(x)<list.get(x)){
                                        hana.set(x,hana.get(x)+1);
                                    }else{
                                        break;
                                    }
                                }
                            }
                        }
                        count+=1;
                    }else{
                        break;
                    }
                }
        }
        System.out.println(count);
        
        
    }
}