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
# coding: utf-8
import sys

input = sys.stdin.readline

N, Q = map(int, input().split())
S = input().strip()
td_list = [input().split() for _ in range(Q)]
dest = [-2] * (N+1)

def sim(i): # i番目のゴーレムの最終結果を得る
  idx = i
  if dest[i] != -2:
    return dest[i]
  for td in td_list:
    if idx == -1:
      dest[i] = -1
      return -1
    elif idx == N:
      dest[i] = N
      return N
    elif td[0] == S[idx]:
      if td[1] == "L":
        idx -= 1
      else:
        idx += 1
  dest[i] = idx
  return idx


# 左側の境界を探索
left, right = -1, N

while right - left != 1:
  mid = (left + right) // 2
  if sim(mid) == -1:
    left = mid
  else:
    right = mid

lb = right

# 右側の境界を探索
left, right = -1, N

while left+1 < right:
  mid = (left + right) // 2
  if sim(mid) == N:
    right = mid
  else:
    left = mid

rb = left

print(rb - lb + 1)

