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.

Input is given from Standard Input in the following format:

```
$N$
$h_1$ $h_2$ $h_3$ $......$ $h_N$
```

Print the minimum number of watering operations required to satisfy the condition.

-   $1 \leq N \leq 100$
-   $0 \leq h_i \leq 100$
-   All values in input are integers.

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).