N,Q = list(map(int,input().split()))
S = list(input())
for _ in range(Q):
    query = input().split()
    if(query[0] == "1"):
        _,i,c = query
        i = int(i) - 1
        S[i] = c
    else:
        _,t = query
        print("Yes" if t in "".join(S) else "No")