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
from collections import Counter
import sys
stdin = sys.stdin
 
sys.setrecursionlimit(10**5) 
 
def li(): return map(int, stdin.readline().split())
def ls(): return stdin.readline().split()
def ns(): return stdin.readline().rstrip()

N, Q = tuple(li())
S = ns()
ops = []
for i in range(Q):
    ops.append(tuple(ls()))

head, tail = 0, N-1
while(ops):
    cur = ops.pop()
    if cur[1] == 'L' and head <N:
        if S[head] == cur[0]:
            head += 1
        if tail <= N-2 and S[tail + 1] == cur[0]:
            tail = min(tail + 1, N-1)
    elif cur[1] == 'R' and tail >= 0:
        if S[tail] == cur[0]:
            tail -= 1
        if head >= 1 and S[head - 1] == cur[0]:
            head = max(0, head-1)
alive = tail - head + 1
# print("tail:{}, head:{}".format(tail, head))
print(max(alive, 0))
