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 <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <vector>

using namespace std;

#define l first
#define r second
#define int long long

int n, m;
string s;
pair<char, char> d[500000];

int simulate(int i)
{
    for (int j = 0; j < m; j++)
    {
        if (d[j].l == s[i])
        {
            if (d[j].r == 'R') i++;
            else i--;
        }
        if (i == -1 || i == n) return i;
    }
    return i;
}

signed main()
{
    cin >> n >> m; 
    cin >> s;
    for (int i = 0; i < m; i++) cin >> d[i].l >> d[i].r;
    int l = -1, r = n;
    while (l + 1 < r)
    {
        int mid = (l + r) / 2;
        if (simulate(mid) == -1) l = mid;
        else r = mid;
    }
    int l2 = -1, r2 = n;
    while (l2 + 1 < r2)
    {
        int mid = (l2 + r2) / 2;
        if (simulate(mid) == n) r2 = mid;
        else l2 = mid;
    }
    cout << min(n, max(0LL, r2 - l - 1));
}
