N,Q = map(int, input().split())
s = input()
gorem=[1]*len(s)
t = [input().split(" ") for i in range(Q)]
for i in t:
    tmp = []
    for j in range(len(s)):
        if s[j]==i[0]:
            tmp.append(j)
    if i[1]=='L':
        for _ in tmp:
            if _ == 0:
                gorem[_]=0
            else:
                gorem[_-1]+=gorem[_]
                gorem[_]-=gorem[_]
    else:
        for _ in tmp:
            if _ == len(s)-1:
                gorem[_]=0
               
            else:
                gorem[_+1]+=gorem[_]
                gorem[_]-=gorem[_]
                
print(sum(gorem))

    
    