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

// clang-format off
#define  range(i, l, r) for (int i = (int)(l); i < (int)(r); ++(i))
#define rrange(i, l, r) for (int i = (int)(r) - 1; i >= (int)(l); --(i))

#define  whole(f, x, ...) ([&](decltype((x)) container) { return (f)(  begin(container),  end(container), ## __VA_ARGS__); })(x)
#define rwhole(f, x, ...) ([&](decltype((x)) container) { return (f)( rbegin(container), rend(container), ## __VA_ARGS__); })(x)

#define endl '\n'
#define debug(x) cerr << "(" << __LINE__ << ")" << #x << ": " << (x) << endl

using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;

// constexpr i32 mod   = 998244353;
constexpr i32 mod   = 1e9 + 7;
constexpr i32 inf   = 1001001001;
constexpr i64 infll = 1001001001001001001ll;

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

struct IoSetup { IoSetup(int x = 15){ cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(x); cerr << fixed << setprecision(x); } } iosetup;

template <typename T = i64> T input() { T x; cin >> x; return x; }

template <typename T> ostream &operator<<(ostream &os, vector<T> &v) { range(i, 0, v.size()) { os << v[i] << (i + 1 != v.size() ? " " : ""); } return os; } 
template <typename T> istream &operator>>(istream &is, vector<T> &v) { for (T &in : v) is >> in; return is; }

template <typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
template <typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p) { is >> p.first >> p.second; return is; }

template <typename T> vector<T> make_vector(size_t a, T b) { return vector<T>(a, b); }
template <typename... Ts> auto make_vector(size_t a, Ts... ts) { return vector<decltype(make_vector(ts...))>(a, make_vector(ts...)); }

template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
// clang-format on

template <typename T> struct BIT {
    int n;
    vector<T> bit;
    // 1-indexed
    BIT(int n_) : n(n_ + 1), bit(n + 1, 0) {}

    T sum(int i) {
        T s(0);
        for (int x = i; x > 0; x -= (x & -x))
            s += bit[x];
        return s;
    }

    void add(int i, T a) {
        if (i == 0)
            return;
        for (int x = i; x <= n; x += (x & -x))
            bit[x] += a;
    }

    // [l, r)
    T query(int l, int r) { return sum(r - 1) - sum(l - 1); }

    int lower_bound(int w) {
        if (w <= 0)
            return 0;
        int x = 0, r = 1;
        while (r < n)
            r <<= 1;
        for (int k = r; k > 0; k >>= 1) {
            if (x + k <= n && bit[x + k] < w) {
                w -= bit[x + k];
                x += k;
            }
        }
        return x + 1;
    }

    // 0-indexed
    T sum0(int i) { return sum(i + 1); }
    void add0(int i, T a) { add(i + 1, a); }
    T query0(int l, int r) { return sum(r) - sum(l); }
};

void solver() {
    i32 N = input();
    string S = '_' + input<string>();
    auto v = make_vector(30, BIT<i64>(N));
    range(i, 1, N + 1) { v[S[i] - 'a'].add(i, 1); }

    i32 Q = input();
    while (Q--) {
        i32 type = input();

        if (type == 1) {
            i32 idx = input();
            char c = input<char>();

            v[S[idx] - 'a'].add(idx, -1);
            S[idx] = c;
            v[S[idx] - 'a'].add(idx, 1);
        } else {
            i32 l = input() - 1, r = input();
            i32 ans = 0;
            range(i, 0, 30) { ans += (v[i].sum(r) - v[i].sum(l) > 0); }

            cout << ans << endl;
        }
    }
}

signed main(int argc, char *argv[]) { solver(); }

Measured memory_bytes: 122012