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[]) {
        try (Scanner in = new Scanner(System.in)) {
            int N = in.nextInt();
            int[] h = new int[N];
            for (int i = 0; i < N; i++) {
                h[i] = in.nextInt();
            }

            int count = 0;
            A: for (;;) {
                for (int i = 0; i < N; i++) {
                    if (h[i] > 0) {
                        decrease(N, h, i);
                        count++;
                        continue A;
                    }
                }
                break;
            }

            System.out.println(count);
        }
    }

    private static void decrease(int N, int[] h, int i) {
        for (int j = i; j < N; j++) {
            if (h[j] <= 0) {
                break;
            }
            h[j]--;
        }
    }

    private static int f(int n) {
        return n % 2 == 0 ? (n / 2) : (3 * n + 1);
    }
}