n,q = map(int,input().split())
ss = input()
s_detail = {}
for i,s in enumerate(ss):
    s_detail.setdefault(s,[]).append(i)
gors = [1] * n
ss_len = len(ss)
for i in range(q):
    s,t = input().split()
    if not s_detail.get(s):
        continue
    for pos in s_detail[s]:
        if gors[pos] == 0:
            continue
        elif pos == 0 and t == "L":
            gors[0] = 0
        elif pos == ss_len - 1 and t == "R":
            gors[-1] = 0
        else:
            gors[pos + (1 if t == "R" else -1)] += gors[pos]
            gors[pos] = 0
#     print(gors)

# print(gors)
print(sum(gors))