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: Runtime Error)

#include <stdio.h>

int array[100];

int water(int l, int r){
    int min=101,min_i=0;
    for(int i=l;i<=r;i++){
        if(array[i]<min){
            min=array[i];
            min_i=i;
        }
    }
    for(int i=l;i<=r;i++) array[i]-=min;
    return min+water(l,min_i-1)+water(min_i+1,r);
}

int main(void){
    int N;
    scanf("%d",&N);
    for(int i=0;i<N;i++) scanf("%d",&array[i]);
    printf("%d\n",water(0,N-1));
    return 0;
}