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 = list(map(int, input().split()))
s = input()
spells =  [input().split() for i in range(Q)]
### 逆順で落ちるゴーレムの位置を戻す
#落ちるゴーレムの端の位置
LDpos = -1
RDpos = N
for sp in spells[::-1]:
    if sp[1] == "L":
        if LDpos < N-1 and s[LDpos+1] == sp[0]:
            LDpos +=1 #LDposのゴーレムは1spell前には一つ右に居た
        if RDpos <= N-1 and s[RDpos] == sp[0]:
            RDpos +=1 #RDposの一つ左(生き残りの右端)は1spell前にこのマスに居れるので境界が一つ戻る
    else:
        if LDpos >= 0 and s[LDpos] == sp[0]:
            LDpos -=1 #LDposの一つ右(生き残りの左端)は1spell前にこのマスに居れるので境界が一つ戻る
        if RDpos > 0 and s[RDpos-1] == sp[0]:
            RDpos -= 1 #RDposのゴーレムは1spell前には一つ左に居た
print(max(RDpos-LDpos-1,0))