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[] H = new int[N];
        int count = 0;
        int max = 0;
        for (int i = 0 ; i < N ; i++) {
            H[i] = sc.nextInt();
            if (max < H[i]) max = H[i];
        }
        int[][] HN = new int[max][N];
        for (int i = 0; i < max; i++) {
            for (int j = 0; j < N ; j++) {
                if (0 < H[j]) {
                    HN[i][j] = 1;
                    H[j]--;
                } else HN[i][j] = 0;
            }
        }
        for (int[] line : HN) {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < line.length; i++) {
                if (i == 0 && line[0] != 0) sb.append(line[i]);
                else if (0 < i && line[i] != line[i-1]) sb.append(line[i]);
                else continue;
            }
            count += sb.toString().split("0").length;
        }
        System.out.println(count);
    }
}