Contest: Task: Related: TaskB

Score : $300$ points

We have a string $X$, which has an even number of characters. Half the characters are `S`

, and the other half are `T`

.

Takahashi, who hates the string `ST`

, will perform the following operation $10^{10000}$ times:

- Among the occurrences of
`ST`

in $X$ as (contiguous) substrings, remove the leftmost one. If there is no occurrence, do nothing.

Find the eventual length of $X$.

- $2 ≦ |X| ≦ 200,000$
- The length of $X$ is even.
- Half the characters in $X$ are
`S`

, and the other half are`T`

.

- In test cases worth $200$ points, $|X| ≦ 200$.

The input is given from Standard Input in the following format:

$X$

Print the eventual length of $X$.

TSTTSS

4

In the $1$-st operation, the $2$-nd and $3$-rd characters of `TSTTSS`

are removed.
$X$ becomes `TTSS`

, and since it does not contain `ST`

anymore, nothing is done in the remaining $10^{10000}-1$ operations.
Thus, the answer is $4$.

SSTTST

0

$X$ will eventually become an empty string: `SSTTST`

⇒ `STST`

⇒ `ST`

⇒ ``.

TSSTTTSS

4

$X$ will become: `TSSTTTSS`

⇒ `TSTTSS`

⇒ `TTSS`

.