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 C (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
int main()
{
    int n;
    scanf("%d", &n);
    int i;
    int h[102];
    for (i = 0; i < n; i++)
        scanf("%d", &h[i]);
    int ans = 0;
    int k = 0, x;
    while (k == 0)
    {
        k = 1;
        x = 0;
        for (i = 0; i < n; i++)
        {
            if (h[i] > 0)
            {
                k = 0;
                if (x == 0)
                {
                    ans++;
                    x = 1;
                }
                h[i]--;
            }
            else
                x = 0;
        }
    }
    printf("%d\n", ans);
    return 0;
}