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(void)
{
  int h[101], n, count = 0;
  int i, j, k;
  
  scanf("%d", &n);
  for( i = 0; i < n; i++){
    scanf("%d", &h[i]);
  }
  
  for( i = 0; i < n; i++ ){
    for( j = i; h[i] != 0; j++ ){
      if( h[i] == 0 ){
        printf("0zo\n");
        break;
      }
      for( k = i; k < n; k++){
        if( h[k] != 0 ){
          h[k] -= 1;
        } else {
          break;
        }
      }
      count++;
    }
  }
  
  printf("%d\n", count);
}