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()
T = []
D = []
for _ in range(Q):
	t, d = input().split()
	T.append(t)
	D.append(d)


ans = 0
left = 0
right = N-1
for i in range(Q-1,-1,-1):
	if D[i] == 'R':
		if T[i] == s[right]:
			right -= 1
			if right == 0:
				print(0)
				exit()
		if left > 0 and s[left-1]==T[i]:
			left -= 1

	else:
		if T[i] == s[left]:
			left += 1
			if left == N-1:
				print(0)
				exit()
		if right < N-1 and s[right+1]==T[i]:
			right += 1
	# print(s[left:right+1])
print(max(0,right-left+1))
