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
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <queue>
#include <iostream>
#include <bitset>
using namespace std;
#define N 200005
int n,t[N],p[N],Q,ans;char s[N],op[10],tp[10];
int main()
{
	scanf("%d%d%s",&n,&Q,s+1);ans=n;
	for(int i=1;i<=Q;i++)scanf("%s%s",op+1,tp+1),p[i]=op[1],t[i]=tp[1]=='L';
	int l=0,r=n+1;
	for(int i=Q;i;i--)
	{
		if(t[i])
		{
			if(l<=n&&s[l+1]==p[i])l++;
			if(r<=n&&s[r]==p[i])r++;
		}else
		{
			if(l&&s[l]==p[i])l--;
			if(r&&s[r-1]==p[i])r--;
		}
		if(l>=r)return puts("0"),0;
	}
	printf("%d\n",r-l-1);
}