/* #region Head */

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pll = pair<ll, ll>;
template <class T>
using vc = vector<T>;
template <class T>
using vvc = vc<vc<T>>;
using vll = vc<ll>;
using vvll = vvc<ll>;
using vld = vc<ld>;
using vvld = vvc<ld>;
using vs = vc<string>;
using vvs = vvc<string>;
template <class T, class U>
using um = unordered_map<T, U>;

#define REP(i, m, n) for (ll i = (m), i##_len = (ll)(n); i < i##_len; ++(i))
#define REPM(i, m, n) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; ++(i))
#define REPR(i, m, n) for (ll i = (m), i##_min = (ll)(n); i >= i##_min; --(i))
#define REPD(i, m, n, d) for (ll i = (m), i##_len = (ll)(n); i < i##_len; i += (d))
#define REPMD(i, m, n, d) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; i += (d))
#define REPI(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)
#define ALL(x) begin(x), end(x)
#define SIZE(x) ((ll)(x).size())
#define PREM(c)   \
    sort(all(c)); \
    for (bool c##p = 1; c##p; c##p = next_permutation(all(c)))
#define UNIQ(v) v.erase(unique(ALL(v)), v.end());

constexpr ll INF = 1'010'000'000'000'000'017LL;
constexpr ll MOD = 1'000'000'007LL; // 1e9 + 7
constexpr ld EPS = 1e-12;
constexpr ld PI = 3.14159265358979323846;

// vector 入力
template <typename T>
istream &operator>>(istream &is, vc<T> &vec)
{
    for (T &x : vec)
        is >> x;
    return is;
}

// vector 出力 (for dump)
template <typename T>
ostream &operator<<(ostream &os, vc<T> &vec)
{
    ll len = SIZE(vec);
    os << "{";
    for (int i = 0; i < len; i++)
        os << vec[i] << (i == len - 1 ? "" : ", ");
    os << "}";
    return os;
}

// vector 出力 (inline)
template <typename T>
ostream &operator>>(ostream &os, vc<T> &vec)
{
    ll len = SIZE(vec);
    for (int i = 0; i < len; i++)
        os << vec[i] << (i == len - 1 ? "\n" : " ");
    return os;
}

// pair 入力
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &pair_var)
{
    is >> pair_var.first >> pair_var.second;
    return is;
}

// pair 出力
template <typename T, typename U>
ostream &operator<<(ostream &os, pair<T, U> &pair_var)
{
    os << "(" << pair_var.first << ", " << pair_var.second << ")";
    return os;
}

// map 出力
template <typename T, typename U>
ostream &operator<<(ostream &os, map<T, U> &map_var)
{
    os << "{";
    REPI(itr, map_var)
    {
        os << *itr;
        itr++;
        if (itr != map_var.end())
            os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

// um 出力
template <typename T, typename U>
ostream &operator<<(ostream &os, um<T, U> &map_var)
{
    os << "{";
    REPI(itr, map_var)
    {
        os << *itr;
        auto itrcp = itr;
        itrcp++;
        if (itrcp != map_var.end())
            os << ", ";
    }
    os << "}";
    return os;
}

// set 出力
template <typename T>
ostream &operator<<(ostream &os, set<T> &set_var)
{
    os << "{";
    REPI(itr, set_var)
    {
        os << *itr;
        itr++;
        if (itr != set_var.end())
            os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

// dump
#define DUMPOUT cerr
void dump_func()
{
    DUMPOUT << endl;
}
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&... tail)
{
    DUMPOUT << head;
    if (sizeof...(Tail) > 0)
    {
        DUMPOUT << ", ";
    }
    dump_func(move(tail)...);
}

// chmax (更新「される」かもしれない値が前)
template <typename T, typename U, typename Comp = less<>>
bool chmax(T &xmax, const U &x, Comp comp = {})
{
    if (comp(xmax, x))
    {
        xmax = x;
        return true;
    }
    return false;
}

// chmin (更新「される」かもしれない値が前)
template <typename T, typename U, typename Comp = less<>>
bool chmin(T &xmin, const U &x, Comp comp = {})
{
    if (comp(x, xmin))
    {
        xmin = x;
        return true;
    }
    return false;
}

// ローカル用
#define DEBUG_

#ifdef DEBUG_
#define DEB
#define dump(...)                                                       \
    DUMPOUT << "  " << string(#__VA_ARGS__) << ": "                     \
            << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" \
            << endl                                                     \
            << "    ",                                                  \
        dump_func(__VA_ARGS__)
#else
#define DEB if (false)
#define dump(...)
#endif

struct AtCoderInitialize
{
    static constexpr int IOS_PREC = 15;
    static constexpr bool AUTOFLUSH = false;

    AtCoderInitialize()
    {
        ios_base::sync_with_stdio(false);
        cin.tie(nullptr);
        cout.tie(nullptr);
        cout << fixed << setprecision(IOS_PREC);
        if (AUTOFLUSH)
            cout << unitbuf;
    }
} ATCODER_INITIALIZE;

string yes = "Yes", no = "No";
// string yes = "YES", no = "NO";

/* #endregion */

template <typename T> // T: 要素
struct SegmentTree
{
    using F = function<T(T, T)>; // 要素と要素をマージする関数．max とか．

    ll n;      // 木のノード数
    F f;       // 区間クエリで使う演算，結合法則を満たす演算．区間最大値のクエリを投げたいなら max 演算．
    T ti;      // 値配列の初期値．演算 f に関する単位元．区間最大値なら単位元は 0. (a>0 なら max(a,0)=max(0,a)=a)
    vc<T> dat; // 1-indexed 値配列 (index は木の根から順に 1 | 2 3 | 4 5 6 7 | 8 9 10 11 12 13 14 15 | ...)

    // コンストラクタ．
    SegmentTree() {}

    // コンストラクタ．
    SegmentTree(F f, T ti) : f(f), ti(ti) {}

    // 指定要素数のセグメント木を初期化する
    void init(ll n_)
    {
        n = 1;
        while (n < n_)
            n <<= 1;
        dat.assign(n << 1, ti);
    }

    // ベクトルからセグメント木を構築する
    void build(const vc<T> &v)
    {
        ll n_ = v.size();
        init(n_);
        for (ll i = 0; i < n_; i++)
            dat[n + i] = v[i];
        for (ll i = n - 1; i; i--)
            dat[i] = f(dat[(i << 1) | 0], dat[(i << 1) | 1]);
    }

    // インデックス k の要素の値を x にする．
    void set_val(ll k, T x)
    {
        dat[k += n] = x;
        while (k >>= 1) // 上へ登って更新していく
            dat[k] = f(dat[(k << 1) | 0], dat[(k << 1) | 1]);
    }

    // 半開区間 [a, b) に対するクエリを実行する
    T query(ll a, ll b)
    {
        if (a >= b)
            return ti;
        // assert(a<b)

        T vl = ti, vr = ti;
        for (ll l = a + n, r = b + n; l < r; l >>= 1, r >>= 1)
        {
            if (l & 1)
                vl = f(vl, dat[l++]);
            if (r & 1)
                vr = f(dat[--r], vr);
        }
        return f(vl, vr);
    }

    template <typename C>
    int find(ll st, C &check, T &acc, ll k, ll l, ll r)
    {
        if (l + 1 == r)
        {
            acc = f(acc, dat[k]);
            return check(acc) ? k - n : -1;
        }
        ll m = (l + r) >> 1;
        if (m <= st)
            return find(st, check, acc, (k << 1) | 1, m, r);
        if (st <= l && !check(f(acc, dat[k])))
        {
            acc = f(acc, dat[k]);
            return -1;
        }
        ll vl = find(st, check, acc, (k << 1) | 0, l, m);
        if (~vl)
            return vl;
        return find(st, check, acc, (k << 1) | 1, m, r);
    }

    // check が真となる要素を探して，そのインデックスを返す．
    template <typename C>
    int find(ll st, C &check)
    {
        T acc = ti;
        return find(st, check, acc, 1, 0, n);
    }
};

ll num_of_bits(ll bits)
{
    bits = (bits & 0x55555555) + (bits >> 1 & 0x55555555);
    bits = (bits & 0x33333333) + (bits >> 2 & 0x33333333);
    bits = (bits & 0x0f0f0f0f) + (bits >> 4 & 0x0f0f0f0f);
    bits = (bits & 0x00ff00ff) + (bits >> 8 & 0x00ff00ff);
    return (bits & 0x0000ffff) + (bits >> 16 & 0x0000ffff);
}

/**
Problem
 */
void solve()
{
    ll n;
    cin >> n;
    string s;
    cin >> s;
    ll q;
    cin >> q;
    vll type(q);
    vll a1(q);
    vc<string> a2(q);
    REP(i, 0, q)
    {
        cin >> type[i] >> a1[i] >> a2[i];
    }

    vll chars(n); // shift
    REP(i, 0, n)
    {
        chars[i] = 1 << (s[i] - 'a');
    }
    // dump(chars);

    auto f = [](ll a, ll b) { return a | b; };
    SegmentTree<ll> seg(f, 0);
    seg.build(chars);
    REP(i, 0, q)
    {
        if (type[i] == 1) // a1 文字目を a2 に変更
        {
            a1[i]--;
            ll val = 1 << (a2[i][0] - 'a');
            // dump(val);
            seg.set_val(a1[i], val);
        }
        else // type = 2: a1 文字目から a2 文字目までに何種類あるか答える
        {
            a1[i]--;
            ll r = stoi(a2[i]);
            // dump(a1[i], a2[i]);
            ll num = seg.query(a1[i], r);
            // dump(num);
            cout << num_of_bits(num) << endl;
        }
    }
}

/**
 * エントリポイント．
 * @return 0.
 */
int main()
{
    solve();
    return 0;
}


Measured memory_bytes: 14364