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 = [int(i) for i in input().split()]
s = input()
td = reversed([input().split() for _ in range(q)])

l = 0
r = n - 1
for t, d in td:
    if d == "L":
        if 0 <= l < n and s[l] == t:
            l = l + 1

        if 0 <= r + 1 < n and s[r + 1] == t:
            r = min(r + 1, n - 1)
    else:
        if 0 <= l-1 < n and s[l - 1] == t:
            l = max(0, l - 1)

        if 0 <= r < n and s[r] == t:
            r = r - 1


'''
    if s[l] == t:
        if d == "L":
            l += 1
        else:
            l -= 1
        l = max(0, min(n - 1, l))
    if s[r] == t:
        if d == "L":
            r += 1
        else:
            r -= 1
        r = max(0, min(n - 1, r))
'''
print(max(0, r-l+1))
