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
#こうけ？
def 解():
    import sys
    input = sys.stdin.readline
    N,Q = [int(_) for _ in input().split()]
    S = " " + input() + " "
    aC = [[ _.rstrip() for _ in  _.split()] for _ in sys.stdin.readlines()]
    iL = 0
    iR = N+1
    for t,d in aC[::-1]:
        if t == S[iL+1] and d == "L" and iL < N+1:
                iL += 1
        elif t == S[iL] and d == "R" and 0 < iL:
                iL -= 1

        if t == S[iR-1] and d == "R" and 0 < iR:
                iR -= 1
        elif t == S[iR] and d == "L" and  iR < N+1:
                iR += 1
    if iL < iR:
        print(iR-iL-1)
    else:
        print(0)
解()
