n, q = map(int, input().split())
s = input()
L = [1 for i in range(n)] #カウント用
x = [list(input().split()) for i in range(q)]
for i in range(q):#呪文ループ
    for j in range(n):#マスループ　左から
    if x[i][0] == s[j]:
        if x[i][1]=='L':
        if j-1>=0:
            L[j-1] +=L[j]
            L[j] = 0
        else:
            L[j] = 0
        else:
        if (j+1)<=(n-1):
            L[j+1] +=L[j]
            L[j] = 0
        else:
            L[j] = 0
print(sum(L))