#include <algorithm>
#include <bitset>
#include <cmath>
#include <complex>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <regex>
#include <set>
#include <stack>
#include <string>
#include <vector>

const int MOD = 1e9 + 7;
const int iINF = 2147483647 / 2;
const long long int llINF = 9223372036854775807 / 2;

using namespace std;
using ll = long long int;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vvvl = vector<vector<vector<ll>>>;

typedef pair<ll, ll> pll;
bool paircomp(const pll &a, const pll &b) {
  if (a.first == b.first)
    return a.second < b.second;
  return a.first < b.first;
}

#define REP(i, n) for (ll i = 0; i < (n); i++)
#define RREP(i, n) for (ll i = (n)-1; i >= 0; i--)
#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define AUTO(i, m) for (auto &i : m)
#define ALL(a) (a).begin(), (a).end()
#define MAX(vec) *std::max_element(vec.begin(), vec.end())
#define MIN(vec) *std::min_element(vec.begin(), vec.end())
#define ARGMAX(vec)                                                            \
  std::distance(vec.begin(), std::max_element(vec.begin(), vec.end()))
#define ARGMIN(vec)                                                            \
  std::distance(vec.begin(), std::min_element(vec.begin(), vec.end()))
#define REV(T) greater<T>()
#define PQ(T) priority_queue<T, vector<T>, greater<T>>
#define VVL(a, b, c) vector<vector<ll>>(a, vector<ll>(b, c))
#define VV(T, a, b, c) vector<vector<T>>(a, vector<T>(b, c))
#define VVVL(a, b, c, d)                                                       \
  vector<vector<vector<ll>>>(a, vector<vector<ll>>(b, vector<ll>(c, d)))
#define VVV(T, a, b, c, d)                                                     \
  vector<vector<vector<T>>>(a, vector<vector<T>>(b, vector<T>(c, d)))
#define SP(a) setprecision(a)
#define SQRT(a) sqrt((long double)(a))
#define DPOW(a, b) pow((long double)(a), (long double)(b))
#define UNIQUE(vec)                                                            \
  do {                                                                         \
    sort(ALL((vec)));                                                          \
    (vec).erase(std::unique(ALL((vec))), (vec).end());                         \
  } while (0)

ll POW(ll n, ll m) {
  if (m == 0) {
    return 1;
  } else if (m % 2 == 0) {
    ll tmp = POW(n, m / 2);
    return (tmp * tmp);
  } else {
    return (n * POW(n, m - 1));
  }
}

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

template <typename Monoid> struct SegmentTree {
  using F = function<Monoid(Monoid, Monoid)>;

  ll sz;
  vector<Monoid> seg;

  const F f;
  const Monoid M1;

  SegmentTree(ll n, const F f, const Monoid &M1) : f(f), M1(M1) {
    sz = 1;
    while (sz < n)
      sz <<= 1;
    seg.assign(2 * sz, M1);
  }

  void set(ll k, const Monoid &x) { seg[k + sz] = x; }

  void build() {
    for (ll k = sz - 1; k > 0; k--) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }

  void update(ll k, const Monoid &x) {
    k += sz;
    seg[k] = x;
    while (k >>= 1) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }

  Monoid query(ll a, ll b) {
    Monoid L = M1, R = M1;
    for (a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
      if (a & 1)
        L = f(L, seg[a++]);
      if (b & 1)
        R = f(seg[--b], R);
    }
    return f(L, R);
  }

  Monoid operator[](const ll &k) const { return seg[k + sz]; }
};

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ll N;
  string S;
  ll Q;
  cin >> N;
  cin >> S;
  cin >> Q;
  SegmentTree<ll> seg(
      1e6, [](ll a, ll b) { return a | b; }, 0);
  // vl T(Q), A(Q);
  // vl B(Q);

  // REP(i, Q) { cin >> T[i] >> A[i] >> B[i]; }
  REP(i, N) { seg.set(i, POW(2, S[i] - 'a')); }
  seg.build();
  // REP(i, N) cout << seg.query(0, 3) << endl;
  vl ans;
  REP(i, Q) {
    ll t, a;
    cin >> t >> a;
    if (t == 1) {
      char b;
      cin >> b;
      // cout << POW(2, (B[i] - 'a')) << endl;
      seg.update(a - 1, POW(2, b - 'a'));
      // cout << B[i] << endl;
      // cout << "pass" << endl;
    } else {
      // cout << A[i] << "," << B[i] << endl;
      ll b;
      cin >> b;
      ll q = seg.query(a - 1, b);
      ll a = 0;
      // cout << q << endl;
      REP(j, 26) {
        a += (q % 2);
        q /= 2;
      }
      // cout << a << endl;
      ans.push_back(a);
    }
  }
  AUTO(a, ans) cout << a << endl;
  return 0;
}


Measured memory_bytes: 17564