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()
Query = [list(input().split()) for i in range(Q)]


# 番兵を設置
S = 'x' + S + 'x'

# 左から何番目のゴーレムまで消えるか二分探索
ok, ng = 0, N + 1
while abs(ok - ng) > 1:
    m = (ok + ng) // 2
    x = (ok + ng) // 2

    for t, d in Query:
        if S[x] != t:
            continue

        if d == 'R':
            x += 1
        if d == 'L':
            x -= 1

        if x == 0:
            ok = m
            break
    else:
        ng = m
Left_ans = ok

# 右から何番目のゴーレムまで消えるか二分探索
ok, ng = N + 1, 0
while abs(ok - ng) > 1:
    m = (ok + ng) // 2
    x = (ok + ng) // 2

    for t, d in Query:
        if S[x] != t:
            continue

        if d == 'R':
            x += 1
        if d == 'L':
            x -= 1

        if x == N + 1:
            ok = m
            break
    else:
        ng = m
Right_ans = ok

print(N - min(N, Left_ans + (N + 1 - Right_ans)))
