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
//exawiz2019_c.cpp
//Sat Mar 30 20:43:05 2019

#include <iostream>
#include <string>
#include <queue>
#include <map>
#include <unordered_map>
#include <vector>
#include <algorithm>
#include <math.h>
#include <set>
#define INTINF 2147483647
#define LLINF 9223372036854775807
using namespace std;
using ll=long long;
typedef pair<int,int> P;

int main(){
	int n,q;
	cin >> n >> q;
	string s;
	cin >> s;

	char t[q],d[q];
	for (int i=0;i<q;i++){
		cin >> t[i] >> d[i];
	}

	//Left.
	int left = 0;
	for (int i=q-1;i>=0;i--){
		if (t[i]==s[left] && d[i]=='L'){
			left++;
		}else if (left>0 && t[i]==s[left-1] && d[i]=='R'){
			left--;
		}
	}

	//Right.
	int right = n-1;
	for (int i=q-1;i>=0;i--){
		if (t[i]==s[right] && d[i]=='R'){
			right--;
		}else if (right<n-1 && t[i]==s[right+1] && d[i]=='L'){
			right++;
		}
	}

	if (left>right){
		cout << 0 << endl;
	}else {
		cout << n-(left + (n-1-right)) << endl;
	}

}