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

def resolve():
    def check(pos):
        for t, d in TD:
            if S[pos] != t:
                continue
            if d == "L":
                pos -= 1
            else:
                pos += 1
            # 左に落ちる
            if pos < 0:
                return -1
            # 右に落ちる
            if pos >= N:
                return 1
        return 0

    N, Q = map(int, input().split())
    S = input()
    TD = [list(input().split()) for _ in range(Q)]

    # 左側の境目: 左橋から最も離れた位置
    ok = -1
    ng = N
    while ng - ok > 1:
        mid = (ok + ng) // 2
        if check(mid) == -1:
            ok = mid
        else:
            ng = mid
    left = ok + 1

    # 右側の境目: 右橋から最も離れた位置
    ok = N
    ng = -1
    while ok - ng > 1:
        mid = (ok + ng) // 2
        if check(mid) == 1:
            ok = mid
        else:
            ng = mid
    right = N - ok

    ans = N - (right + left)
    print(ans)


if __name__ == "__main__":
    resolve()
