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


Output

Print the answer.

Examples

Input

3 4
ABC
A L
B L
B R
A R


Output

2


Input

8 3
AABCBDBA
A L
B R
A R


Output

5


Input

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
# /usr/bin/python
# -*- coding: utf-8 -*-
#
import sys


N,Q = map(int, sys.stdin.readline().rstrip().split())
s = [""] + list(str(input())) + [""]
td = [["" for j in range(2)] for i in range(Q)]
for i in range(Q):
  td[i] = list(map(str, sys.stdin.readline().rstrip().split()))


# idx の位置の文字が左に消えるなら "L",
# 右に消えるなら "R", そうでなければ "F"
def check(idx):
  for t,d in td:
    if s[idx] == t:
      if d == "L":
        idx -= 1
      else:
        idx += 1
    if idx == 0:
      return "L"
    elif idx == N+1:
      return "R"
  return "F"


if __name__ == "__main__":
  # L のポイントをbinary search
  l,r = [0,N+1]
  while(r-l > 1):
    mid = (r+l) // 2
    if check(mid) == "L":
      l = mid
    else:
      r = mid
  lp = l

  # R のポイントをbinary search
  l,r = [0,N+1]
  while(r-l > 1):
    mid = (r+l) // 2
    if check(mid) == "R":
      r = mid
    else:
      l = mid
  rp = r-1

  print(rp-lp)
