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
input = raw_input

N,Q = map(int,input().split(" "))
s=list(input())
ju = []
for i in range(Q):
    ju.append(input().split(" "))

def isdeadleft(xp):
    oxp = xp
    for i in range(Q):
        com = ju[i]
        if s[xp] == com[0]:
            if com[1] == "L":
                xp -= 1
            else:
                xp += 1
        if xp < 0:
            return True
        if xp > N-1:
            xp = N-1
    return False

def isdeadright(xp):
    oxp = xp
    for i in range(Q):
        com = ju[i]
        if s[xp] == com[0]:
            if com[1] == "L":
                xp -= 1
            else:
                xp += 1
        if xp < 0:
            xp = 0
        if xp > N-1:
            return True
    return False

def mid(x1,x2):
    return int((x1+x2)/2)

if isdeadleft(N-1) or isdeadright(0):
    print(0)
    exit()

#left
p1 = 0
p3 = N-1
p2 = mid(p1,p3)
while p3 - p1 != 1:
    if isdeadleft(p2):
        p1,p2 = p2,mid(p2,p3)
    else:
        p2,p3 = mid(p1,p2),p2
if isdeadleft(p1):
    p = p3
else:
    p = p1
#right
p1 = 0
p3 = N-1
p2 = mid(p1,p3)
while p3 - p1 != 1:
    if isdeadright(p2):
        p2,p3 = mid(p1,p2),p2
    else:
        p1,p2 = p2,mid(p2,p3)
if isdeadright(p3):
    q = p1
else:
    q = p3

if p > q:
    print(0)
else:
    print(q-p+1)
