import collections

N = int(input())
S = input()
Q = int(input())
querys = [list(map(str, input().split())) for i in range(Q)]
for i in range(Q):
    query = querys[i]
    if query[0] == "1":
        qi = int(query[1])
        S = S[:qi-1] + query[2] + S[qi:]
    else:
        c = collections.Counter(S[int(query[1]) - 1:int(query[2])])
        print(len(c))