Snuke the Wizard

AtCoder

IDexawizards2019_c

Time2000ms

Memory256MB

Difficulty—

There are $N$ squares numbered $1$ to $N$ from left to right. Each square has a character written on it, and Square $i$ has a letter $s_i$. Besides, there is initially one golem on each square. Snuke cast $Q$ spells to move the golems. The $i$\-th spell consisted of two characters $t_i$ and $d_i$, where $d_i$ is `L` or `R`. When Snuke cast this spell, for each square with the character $t_i$, all golems on that square moved to the square adjacent to the left if $d_i$ is `L`, and moved to the square adjacent to the right if $d_i$ is `R`. However, when a golem tried to move left from Square $1$ or move right from Square $N$, it disappeared. Find the number of golems remaining after Snuke cast the $Q$ spells. ## Constraints * $1 \leq N,Q \leq 2 \times 10^{5}$ * $|s| = N$ * $s_i$ and $t_i$ are uppercase English letters. * $d_i$ is `L` or `R`. ## Input Input is given from Standard Input in the following format: $N$ $Q$ $s$ $t_1$ $d_1$ $\vdots$ $t_{Q}$ $d_Q$ [samples]

Samples

Input #1

3 4
ABC
A L
B L
B R
A R

Output #1

2

*   Initially, there is one golem on each square.
*   In the first spell, the golem on Square $1$ tries to move left and disappears.
*   In the second spell, the golem on Square $2$ moves left.
*   In the third spell, no golem moves.
*   In the fourth spell, the golem on Square $1$ moves right.
*   After the four spells are cast, there is one golem on Square $2$ and one golem on Square $3$, for a total of two golems remaining.

Input #2

8 3
AABCBDBA
A L
B R
A R

Output #2

5

*   After the three spells are cast, there is one golem on Square $2$, two golems on Square $4$ and two golems on Square $6$, for a total of five golems remaining.
*   Note that a single spell may move multiple golems.

Input #3

10 15
SNCZWRCEWB
B R
R R
E R
W R
Z L
S R
Q L
W L
B R
C L
A L
N L
E R
Z L
S L

Output #3

API Response (JSON)

{
  "problem": {
    "name": "Snuke the Wizard",
    "description": {
      "content": "There are $N$ squares numbered $1$ to $N$ from left to right. Each square has a character written on it, and Square $i$ has a letter $s_i$. Besides, there is initially one golem on each square. Snuke ",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "exawizards2019_c"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "There are $N$ squares numbered $1$ to $N$ from left to right. Each square has a character written on it, and Square $i$ has a letter $s_i$. Besides, there is initially one golem on each square.\nSnuke ...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments