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<bits/stdc++.h>
#define REP(i,n) for(int i=0;i<(n);++i)
using namespace std;

int main(){
	int n,q;
	cin>>n>>q;
	vector<char> s(n+2);
	s[0]='n';
	s[n+1]='n';
	for(int i=1;i<=n;++i) cin>>s[i];
	
	vector<char> t(q),d(q);
	REP(i,q){
		cin>>t[i]>>d[i];
	}
	
	int left=0,right=n+1;
	for(int i=q-1;i>=0;--i){
		if(d[i]=='L'){
			if(t[i]==s[left+1]) left++;//point.
			if(t[i]==s[right]) right++;
		}else{
			if(t[i]==s[right-1]) right--;//point.
			if(t[i]==s[left]) left--;
		}
	}
	
	cout<<max(0,right-left-1)<<endl;
	return 0;
}//解答解説参考.