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() + ' '

ps = [0, N+1]
dirs = { 'L': 1, 'R': -1 }
QS = [input().split() for _ in range(Q)][::-1]
p = 0
for t, d in QS:
  di = dirs[d]
  np = p + di
  if 0 <= np <= N+1 and di == 1 and S[np] == t:
    p += 1
  if 0 <= np <= N+1 and di == -1 and S[p] == t:
    p -= 1
p1 = p

p = N+1
for t, d in QS:
  di = dirs[d]
  np = p + di
  if 0 <= np <= N+1 and di == -1 and S[np] == t:
    p -= 1
  if 0 <= np <= N+1 and di == 1 and S[p] == t:
    p += 1
p2 = p
print(max(0, p2 - p1 - 1))