#ifndef DEBUG
#  define NDEBUG
#endif
#include <iostream>
#include <string>
#include <iterator>
#include <utility>
#include <type_traits>
#include <limits>
#include <cassert>
#include <vector>

using namespace std;

// template {{{
// misc {{{
using Z = int;
[[maybe_unused]]
constexpr Z INF = numeric_limits<Z>::max() / 3;
// }}}

// debug {{{
template <class T>
using enable_if_sequence_t = enable_if_t<
  is_same<
    typename iterator_traits<
      typename remove_cv_t<remove_reference_t<T>>::iterator
    >::iterator_category,
    random_access_iterator_tag>{}>;
#ifdef NDEBUG
# define dump(x)
# define debug if (0)
template <class T>
inline T&& ix(T&& value) { return value; }
template <class T, class Index, class... Indices, class = enable_if_sequence_t<T>>
inline auto&& ix(T&& container, Index index, Indices... indices) {
  return ix(container[index], indices...);
}
#else
# define dump(x) do { \
    cerr << "\e[33m[dump: " << __LINE__ << "] " << (#x) << " = " << x << "\e[0m" << endl; \
  } while (0);
# define debug
template <class T>
inline auto&& ix_impl([[maybe_unused]] int line, [[maybe_unused]] const char* code, T&& value) {
  return value;
}
template <class T, class Index, class... Indices, class = enable_if_sequence_t<T>>
inline auto&& ix_impl(int line, const char* code, T&& container, Index index, Indices... indices) {
  if (index < 0) {
    cerr << "\e[31mix: negative index at line " << line << ", ix(" << code << ")\e[0m" << endl;
    exit(1);
  }
  int size = container.size();
  if (index >= size) {
    cerr << "\e[31mix: index out of range at line " << line << ", ix(" << code << ")\n"
      << "index = " << index << " whereas size = " << size << "\e[0m" << endl;
    exit(1);
  }
  return ix_impl(line, code, container[index], indices...);
}
#define ix(...) ix_impl(__LINE__, #__VA_ARGS__, __VA_ARGS__)
#endif
// }}}

// IO {{{
template <class T>
false_type is_container_impl(...);
template <class T, class = typename T::iterator>
true_type is_container_impl(T);
template <class T>
struct is_container : decltype(is_container_impl<T>(declval<T>())) {};
template <>
struct is_container <string> : std::false_type {};
template <class Container, class = enable_if_t<is_container<Container>{}>>
istream& operator>> (istream& is, Container& cont) {
  for (auto& v : cont) is >> v;
  return is;
}
template <class Container, class = enable_if_t<is_container<Container>{}>>
ostream& operator<< (ostream& os, Container const& cont) {
  bool first = true;
  constexpr char sep =
    is_container<typename Container::value_type>{} ? '\n' : ' ';
  for (auto const& v : cont) {
    if (!first) {
      os << sep;
    }
    first = false;
    os << v;
  }
  return os;
}
template <class T, class U>
ostream& operator<< (ostream& os, pair<T, U> p) {
  os << '(' << p.first << ", " << p.second << ')';
  return os;
}
// }}}
// }}}

class segtree {
  public:
    int size;
    vector<Z> data;
    Z query_impl(int left, int right, int node, int a, int b) {
      if (right <= a || b <= left) return 0;
      if (left <= a && b <= right) return data[node];
      Z lv = query_impl(left, right, 2 * node + 1, a, (a + b) / 2),
        rv = query_impl(left, right, 2 * node + 2, (a + b) / 2, b);
      return lv | rv;
    }
  public:
    segtree(Z n) {
      size = 1;
      while (size < n) size *= 2;
      data.resize(size * 2 - 1);
    }

    Z query(int left, int right) {
      return query_impl(left, right, 0, 0, size);
    }

    void update(int i, Z v) {
      int node = i + size - 1;
      data[node] = v;
      while (node > 0) {
        node = (node - 1) / 2;
        data[node] = data[2 * node + 1] | data[2 * node + 2];
      }
    }
};


int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  Z N, Q;
  string S;
  cin >> N >> S >> Q;
  segtree t(N);
  for (auto i = 0; i < N; i++)
    t.update(i, 1 << (S[i] - 'a'));
  dump(t.data);
  for (auto i = 0; i < Q; i++) {
    Z q;
    cin >> q;
    if (q == 1) {
      Z j;
      char c;
      cin >> j >> c;
      j--;
      t.update(j, 1 << (c - 'a'));
      dump(t.data);
    }
    else {
      Z l, r;
      cin >> l >> r;
      l--; r--;
      cout << __builtin_popcount(t.query(l, r + 1)) << endl;
    }
  }
}



Measured memory_bytes: 5148