//
//  main.cpp
//

#include <algorithm>
#include <array>
#include <assert.h>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <math.h>
#include <memory>
#include <memory>
#include <queue>
#include <random>
#include <set>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

using ll = int64_t;
using ull = uint64_t;
constexpr ll LL_MAX = numeric_limits<ll>::max();
constexpr ull ULL_MAX = numeric_limits<ull>::max();

template<typename T>
vector<T> make_vec_nd(T init, ll size) {
	return vector<T>(size, init);
}
template<typename T, typename... Args>
auto make_vec_nd(T init, ll size, Args... rest) {
	auto inner = make_vec_nd(init, rest...);
	return vector<decltype(inner)>(size, inner);
}

#define rep(i, a, b) for (ll i = (a); i < (b); i++)
#define rrep(i, a, b) for (ll i = (a)-1; i >= (b); i--)

template<typename Monoid>
struct SegmentTree {
    using Op = function<Monoid(const Monoid& lhs, const Monoid& rhs)>;
    ll width;
    vector<Monoid> node;
    Op op;
    Monoid unit;
    
    SegmentTree(ll N, Op op, Monoid unit)
    : SegmentTree(vector<Monoid>(N, unit), op, unit) {}
    SegmentTree(const vector<Monoid>& elems, Op op, Monoid unit)
    : op(op)
    , unit(unit) {
        width = 1;
        while (width < elems.size()) {
            width *= 2;
        }
        node.resize(2 * width - 1, unit);
        for (size_t i = 0; i < elems.size(); i++) {
            node[i + width - 1] = elems[i];
        }
        for (size_t i = width - 2; i != numeric_limits<size_t>::max(); i--) {
            node[i] = op(node[2 * i + 1], node[2 * i + 2]);
        }
    }
    void update(ll idx, Monoid elem) {
        idx += width - 1;
        node[idx] = elem;
        while (idx >= 1) {
            idx = (idx - 1) / 2;
            node[idx] = op(node[2 * idx + 1], node[2 * idx + 2]);
        }
    }
    Monoid query(ll a, ll b, ll root = 0) const {
        assert(0 <= a && b <= width);
        ll left = root, right = root;
        while (left < width - 1) {
            left = 2 * left + 1;
        }
        left -= (width - 1);
        while (right < width - 1) {
            right = 2 * right + 2;
        }
        right -= (width - 1);
        right++;
        if (right <= a || b <= left) {
            return unit;
        }
        if (a <= left && right <= b) {
            return node[root];
        }
        Monoid ans_l = query(a, b, 2 * root + 1);
        Monoid ans_r = query(a, b, 2 * root + 2);
        return op(ans_l, ans_r);
    }
    Monoid operator[](size_t idx) { return query(idx, idx + 1); }
};

int main() {
    ll N;
    cin >> N;
    vector<SegmentTree<bool>> trees(26,
                                    SegmentTree<bool>(N, [](bool lhs, bool rhs){ return lhs || rhs; }, false));
    string S;
    cin >> S;
    rep(i,0,N) {
        ll idx = S[i] - 'a';
        trees[idx].update(i, true);
    }
    ll Q;
    cin >> Q;
    rep(q,0,Q) {
        ll type;
        cin >> type;
        if (type == 1) {
            ll i;
            cin >> i;
            i--;
            char c;
            cin >> c;
            if (S[i] == c) {
                continue;
            }
            trees[S[i] - 'a'].update(i, false);
            trees[c - 'a'].update(i, true);
            S[i] = c;
        } else {
            ll l, r;
            cin >> l >> r;
            l--;
            ll cnt = 0;
            rep(i,0,26) {
                cnt += trees[i].query(l, r);
            }
            cout << cnt << endl;
        }
    }
}


Measured memory_bytes: 4544