p03081 ExaWizards 2019 - Snuke the Wizard
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
```python
n, q = map(int, input().split())
s = input()

o = []
for _ in range(q):
    t, d = input().split()
    o.append((t, d))


def check(x):
    cur = s[x]
    ind = x
    for i in range(q):
        if o[i][0] == cur:
            if o[i][1] == 'L':
                ind -= 1
                if ind < 0:
                    return "LEFT"
                cur = s[ind]
            else:
                ind += 1
                if ind > n-1:
                    return "RIGHT"
                cur = s[ind]
    return "MID"


ans = n

bottom = -1
top = n

while top - bottom > 1:
    mid = (top+bottom)//2
    if check(mid) == "LEFT":
        bottom = mid
    else:
        top = mid

ans -= 1+bottom

bottom = -1
top = n

while top - bottom > 1:
    mid = (top+bottom)//2
    if check(mid) == "RIGHT":
        top = mid
    else:
        bottom = mid

ans -= n-top

print(ans)
```