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

#define int long long
#define double long double
#define rep(i, n) for (int i = 0; i < (n); i++)
#define reps(i, n) for (int i = 1; i <= (n); i++)
#define all(x) begin(x), end(x)
#define uniq(x) (x).erase(unique(all(x)), end(x))
#define bit(n) (1LL << (n))
#define dump(x) cerr << #x " = " << (x) << endl
using vint = vector<int>;
using vvint = vector<vint>;
using pint = pair<int, int>;
using vpint = vector<pint>;
template<typename T> using priority_queue_rev = priority_queue<T, vector<T>, greater<T>>;
constexpr double pi = 3.1415926535897932384626433832795028L;
constexpr int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};
constexpr int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
int gcd(int a, int b) {
    while (b) { swap(a %= b, b); }
    return a;
}
int lcm(int a, int b) { return a / gcd(a, b) * b; }
template<typename T> void fin(T mes) {
    cout << mes << endl;
    exit(0);
}
template<typename T, typename U> bool chmax(T &a, const U &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template<typename T, typename U> bool chmin(T &a, const U &b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T, typename U> ostream &operator<<(ostream &os, const pair<T, U> &rhs) {
    os << "(" << rhs.first << ", " << rhs.second << ")";
    return os;
}
template<typename T> ostream &operator<<(ostream &os, const vector<T> &rhs) {
    os << "{";
    for (auto itr = rhs.begin(); itr != rhs.end(); itr++) {
        os << *itr << (next(itr) != rhs.end() ? ", " : "");
    }
    os << "}";
    return os;
}
struct setup {
    static constexpr int PREC = 20;
    setup() {
        cout << fixed << setprecision(PREC);
        cerr << fixed << setprecision(PREC);
    };
} setup;
template<typename T>
struct segment_tree {
    int n;
    T zero;
    std::vector<T> data;
    int get_size(int n_) const {
        int ret = 1;
        while (ret < n_) { ret <<= 1; }
        return ret;
    }
    segment_tree(int n_, T zero = T()) : n(get_size(n_)), zero(zero), data(n << 1, zero) {}
    template<typename I> segment_tree(I begin, I end, T zero = T())
        : n(get_size(end - begin)), zero(zero), data(n << 1) {
        std::copy(begin, end, data.begin() + n);
        for (int i = n - 1; i > 0; i--) { data[i] = data[i << 1] + data[(i << 1) + 1]; }
    }
    void set(int i, const T &x) {
        data[i += n] = x;
        while (i >>= 1) { data[i] = data[i << 1] + data[(i << 1) + 1]; }
    }
    T operator[](int i) const { return data[i + n]; }
    T get_sum(int l, int r) const {
        if (l < 0) { l = 0; }
        if (r > n) { r = n; }
        T a = zero, b = zero;
        for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
            if (l & 1) { a = a + data[l++]; }
            if (r & 1) { b = data[--r] + b; }
        }
        return a + b;
    }
};
struct monoid {
    int alph;
    monoid() : alph(0) {}
    monoid(int alph) : alph(alph) {}
    monoid &operator+=(const monoid &rhs) {
        alph |= rhs.alph;
        return *this;
    }
    monoid operator+(const monoid rhs) const { return monoid(*this) += rhs; }
};
int N, Q;
string S;
signed main() {
    cin >> N >> S >> Q;
    vector<monoid> vec(N);
    rep(i, N) { vec[i] = bit(S[i] - 'a'); }
    segment_tree<monoid> st(all(vec));
    rep(i, Q) {
        int type;
        cin >> type;
        if (type == 1) {
            int k;
            char c;
            cin >> k >> c;
            k--;
            st.set(k, bit(c - 'a'));
        } else {
            int l, r;
            cin >> l >> r;
            l--, r--;
            monoid m = st.get_sum(l, r + 1);
            int cnt = 0;
            rep(j, 26) {
                cnt += (m.alph >> j) & 1LL;
            }
            cout << cnt << endl;
        }
    }

}


Measured memory_bytes: 13060