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 = list(input())
TD = [tuple(input().split()) for _ in range(Q)]

def bs_l(f, s, e):
	if s==e:
		return s if f(s) else s+1

	c = (s+e)//2
	if f(c):
		#左
		return bs_l(f, s, c if c == s else c-1)
	else:
		#右
		return bs_l(f, c if c == e else c+1, e)

def bs_r(f, s, e):
	if s==e:
		return s if f(s) else s-1

	c = (s+e)//2
	if not f(c):
		#左
		return bs_r(f, s, c if c == s else c-1)
	else:
		#右
		return bs_r(f, c if c == e else c+1, e)

def isAlive(c):
	for t, d in TD:
		if S[c] == t:
			c += 1 if "R" == d else -1
			if c < 0 or N <= c:
				return False
	return True

S, E = bs_l(isAlive, 0, N-1), bs_r(isAlive, 0, N-1)
print(max(E-S+1, 0))
