n, q = map(int, input().split())
s = input()
ls = [1] * n
for _ in range(q):
    t, d = input().split()
    ts = [0] * n
    if t in s:
        if d == "L":
            for i in range(s.index(t),n):
                if s[i] == t:
                    if i == 0:
                        ls[i] = 0
                    else:
                        ts[i - 1] = ls[i]
                        ls[i] = 0
        else:
            for i in range(s.index(t),n):
                if s[i] == t:
                    if i == n-1:
                        ls[i] = 0
                    else:
                        ts[i + 1] = ls[i]
                        ls[i] = 0
        for i in range(n):
            ls[i] += ts[i]
            

print(sum(ls))