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()
tds = [input().split() for _ in range(Q)]

barely_safe_left = 0
barely_safe_right = N - 1
for t, d in reversed(tds):
    if barely_safe_left >= N or barely_safe_right < 0:
        break
    if s[barely_safe_left] == t and d == 'L':
        barely_safe_left += 1
    if s[barely_safe_right] == t and d == 'R':
        barely_safe_right -= 1
    if barely_safe_left - 1 >= 0 and s[barely_safe_left - 1] == t and d == 'R':
        barely_safe_left -= 1
    if barely_safe_right + 1 < N and s[barely_safe_right + 1] == t and d == 'L':
        barely_safe_right += 1

if barely_safe_left > barely_safe_right:
    print(0)
else:
    print(barely_safe_right - barely_safe_left + 1)
    