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
# -*- coding: utf-8 -*-
import sys
import copy
import collections
from bisect import bisect_left
	
def main():
	N, Q = map(int, input().split())
	S = "_" + input() + "_"
	
	TD = []
	for _ in range(Q):
		tmp = input().split(" ")
		t = tmp[0]
		d = tmp[1]
		TD.append((t, d))
		
	TD.reverse()
	gake_L = 0
	gake_R = N - 1 + 2
	
	for i, val in enumerate(TD):
		t, d = val
		
		if d == "R":
			if t == S[gake_R-1]:
				gake_R -= 1
			if t == S[gake_L]:
				gake_L -= 1
		
		if d == "L":
			if t == S[gake_R]:
				gake_R += 1
			if t == S[gake_L+1]:
				gake_L += 1
	
	print(max(0, gake_R-gake_L-1))
	
	
if __name__ == "__main__":
	main()
