output_description: Print the answer.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N Q
      s
      t_1 d_1
      \vdots
      t_{Q} d_Q
attempt: # -*- coding: utf-8 -*-
  
  # WAなのは分かってるけど良いアイデアだと思ったのが空振って悔しいのでとりあえず投稿
  
  from sys import stdin
  
  
  def load():
      n = stdin.readline()
      return n
  
  
  n, q = [int(x) for x in load().strip().split(" ")]
  n = int(n)
  
  index = {}
  for i, x in enumerate(load().strip()):
      if x not in index:
          index[x] = [i]
      else:
          index[x].append(i)
  
  move = {x: 0 for x in index.keys()}
  
  for line in stdin.readlines():
      t, d = line.strip().split(" ")
  
      if t not in move:
          continue
  
      if d == "L":
          move[t] -= 1
      else:
          move[t] += 1
  
  living_golem = n
  for x, hosu in move.items():
      for target in index[x]:
          if target + hosu >= n or target - hosu < 0:
              living_golem -= 1
  print(living_golem)
  
problem_description: Statement
  
  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.
samples: [{"input": "3 4\n    ABC\n    A L\n    B L\n    B R\n    A R", "output": "2\n    \n\n  * Initially, there is one golem on each square.\n  * In the first spell, the golem on Square 1 tries to move left and disappears.\n  * In the second spell, the golem on Square 2 moves left.\n  * In the third spell, no golem moves.\n  * In the fourth spell, the golem on Square 1 moves right.\n  * 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.\n\n* * *"}, {"input": "8 3\n    AABCBDBA\n    A L\n    B R\n    A R", "output": "5\n    \n\n  * 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.\n  * Note that a single spell may move multiple golems.\n\n* * *"}, {"input": "10 15\n    SNCZWRCEWB\n    B R\n    R R\n    E R\n    W R\n    Z L\n    S R\n    Q L\n    W L\n    B R\n    C L\n    A L\n    N L\n    E R\n    Z L\n    S L", "output": "3"}]