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
#a,b,c = [int(i) for i in input().split()]

import sys
input = sys.stdin.readline

n,q = [int(i) for i in input().split()]
s=input()
td = [[i for i in input().split()] for _ in [0]*q]
td=td[::-1]

#print(n,q,td)

l=-1; r=n
for t,d in td:
    if d=="L":
        if l!=n-1:
            moji=s[l+1]
            if moji == t:
                l+=1
        moji=s[r]
        if moji == t:
            r+=1
            

    if d=="R":
        if r!=0:
            moji=s[r-1]
            if moji == t:
                r-=1
        moji=s[l]
        if moji == t:
            l-=1
        
    
#    print(l,r)
if l < r:
    print(n-(l+1)-(n-r))
else:
    print(0)


        