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()
TD=[]
for q in range(Q):
	TD.append(list(map(str,input().split())))
L=S[:]
R=S[::-1]
lw=0
rw=0
ansl = 0
ansr = 0
for q in range(Q)[::-1]:
	if TD[q][1] == 'L': 
		if TD[q][0] == L[lw]: #now word is OK
			ansl = max(ansl, lw+1)
			if lw+1 == N: #all clear
				break
			else:
				lw += 1
		if rw>0: 
			if TD[q][0] == R[rw-1]: #before word is wrong
				ansr = max(ansr-1, 0)
				rw -=1
	if TD[q][1] == 'R':
		if TD[q][0] == R[rw]: #now word is OK
			ansr = max(ansr, rw+1)
			if rw+1 == N: #all clear
				break 
			else:
				rw += 1
		if lw>0: 
			if TD[q][0] == L[lw-1]: #before word is wrong
				ansl = max(ansl-1, 0)
				lw -=1


print(max(0,N-(ansr+ansl)))