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 = list(map(int, input().split()))
s = list(input())

D = [0 for i in range(N)]

ql = []
for i in range(Q):
	t, d = list(input().split())
	ql.append([t, d])

x = 0
y = N - 1
for i in range(Q):
	if ql[-1 - i][1] == "L":
		if y < N - 1:
			if ql[-1 - i][0] == s[y + 1]:
				D[y + 1] = 0
				y += 1
		if x < N:
			if ql[-1 - i][0] == s[x]:
				D[x] = 1
				x += 1

	else:
		if x > 0:
			if ql[-1 - i][0] == s[x - 1]:
				D[x - 1] = 0
				x -= 1
		if y >= 0:
			if ql[-1 - i][0] == s[y]:
				D[y] = 1
				y -= 1

print(N - sum(D))