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>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n); i++)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
using P = pair<int, int>;
const int INF = 1e9;
const long long LINF = 1e18;
const long long MOD = 1e9 + 7;

signed main(){
	int n,q;
	cin >> n >> q;
	string s;
	cin >> s;
	char t[q],d[q];
	rep(i,q){
		cin >> t[i] >> d[i];
	}
	int left = 0, right = n;
	for(int i = q - 1; i >= 0; i--){
		if(t[i] == s[left] && d[i] == 'L') left++;
		if(t[i] == s[right - 1] && d[i] == 'R') right--;
		if(left > 0 && t[i] == s[left - 1] && d[i] == 'R') left--;
		if(right < n && t[i] == s[right] && d[i] == 'L') right++;
	}
	cout << max(0, right - left) << endl;
	return 0;
}