N, Q = [int(s) for s in input().split()]
S = input()

for _ in range(Q):
    cmd, *query = input().split()
    cmd = int(cmd)

    if cmd == 1:
        i, c = query
        i = int(i) - 1

        list_s = list(S)
        list_s[i] = c
        S = "".join(list_s)

    else:
        T = query[0]
        print("Yes" if T in S else "No")