101162: [AtCoder]ABC116 C - Grand Garden

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