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
def is_left_removed(i, S, td):
  direction = {'L': -1, 'R': +1}
  for t, d in td:
    if S[i] == t:
      i += direction[d]
    if i < 0:
      return True
    if i >= N:
      return False
  return False
def is_right_removed(i, S, td):
  direction = {'L': -1, 'R': +1}
  for t, d in td:
    if S[i] == t:
      i += direction[d]
    if i >= N:
      return True
    if i < 0:
      return False
  return False

N, Q = map(int, raw_input().split())
s = raw_input()
td = [raw_input().split() for _ in range(Q)]

# left
l = 0
r = N - 1
l_res = -1
while (l <= r):
  target = (r + l) / 2
  if is_left_removed(target, s, td):
    l = target + 1
    l_res = target
  else:
    r = target - 1

# right
l = 0
r = N - 1
r_res = N
while (l <= r):
  target = (r + l) / 2
  if is_right_removed(target, s, td):
    r = target - 1
    r_res = target
  else:
    l = target + 1

print N - min(N, l_res + 1 + N - r_res)