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=list(input())
p=[tuple(input().split())for i in range(q)]
def judge_l(x):
    for(k,v)in p:
        if k==s[x]:
            if v=="L":
                x-=1
            else:
                x+=1
        if x==-1:
            return True
        elif x==n:
            return False
    return False

def judge_r(x):
    for(k,v)in p:
        if k==s[x]:
            if v=="L":
                x-=1
            else:
                x+=1
        if x==-1:
            return False
        elif x==n:
            return True
    return False

ok=-1
ng=n

while abs(ok-ng)>1:
    mid=(ok+ng)//2
    if judge_l(mid):
        ok=mid
    else:
        ng=mid
l=ok+1

ok=n
ng=-1

while abs(ok-ng)>1:
    mid=(ok+ng)//2
    if judge_r(mid):
        ok=mid
    else:
        ng=mid
r=n-ok
#print(l,r)
print(max(n-l-r,0))
