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
N,Q = map(int, input().split())
S = input()
C = [tuple(map(str, input().split())) for _ in range(Q)]
C = C[::-1]

left = -1
right = N

for (t,d) in C:
  if ('L' == d):
    if (S[left+1] == t):
      left += 1
      if (N-1 <= left):
        print(0)
        exit()
    if (right < N):
      if (S[right] == t):
        right += 1
        if (N < right):
          right = N
  else:
    if (S[right-1] == t):
      right -= 1
      if (right <= 0):
        print(0)
        exit()
    if (-1 < left):
      if (S[left] == t):
        left -= 1
        if (left < -1):
          left = -1

print(right - left - 1)
