#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <stack>
#include <queue>
#include <bitset>
#include <numeric>
#include <cassert>
#include <array>
#include <memory>
#include <random>
#include <functional>
#include <complex>
#ifdef DEBUG
#include "./Lib/debug.hpp"
#include "./Lib/Timer.hpp"
#include "./Lib/sample.hpp"
#else
#define dump(...)
#endif

/* (=＾o＾=) */
//#define int ll

/* macro */
#define FOR(i, b, e) for(ll i = (ll)(b); i < (ll)(e); ++i)
#define RFOR(i, b, e) for(ll i = (ll)(e-1); i >= (ll)(b); --i)
#define REP(i, n) FOR(i, 0, n)
#define RREP(i, n) RFOR(i, 0, n)
#define REPC(x,c) for(const auto& x:(c))
#define REPI2(it,b,e) for(auto it = (b); it != (e); ++it)
#define REPI(it,c) REPI2(it, (c).begin(), (c).end())
#define RREPI(it,c) REPI2(it, (c).rbegin(), (c).rend())
#define REPI_ERACE2(it, b, e) for(auto it = (b); it != (e);)
#define REPI_ERACE(it, c) REPI_ERACE2(it, (c).begin(), (c).end())
#define ALL(x) (x).begin(),(x).end()
#define cauto const auto&
/* macro func */
template<class T>
inline void sort(T& t) { std::sort(ALL(t)); }
template<class T>
inline void rsort(T& t) { std::sort((t).rbegin(), (t).rend()); }
template<class T>
inline void unique(T& t) { (t).erase(unique((t).begin(), (t).end()), (t).end()); }
template<class T, class S>
inline bool chmax(T& t, const S& s) { if (s > t) { t = s; return true; } return false; }
template<class T, class S>
inline bool chmaxE(T& t, const S& s) { if (s >= t) { t = s; return true; } return false; }
template<class T, class S>
inline bool chmin(T& t, const S& s) { if (s < t) { t = s; return true; } return false; }
inline void BR() { std::cout << "\n"; }

/* type define */
using ll = long long;
using PAIR = std::pair<ll, ll>;
using VS = std::vector<std::string>;
using VL = std::vector<long long>;
using VVL = std::vector<VL>;
using VVVL = std::vector<VVL>;
using VD = std::vector<double>;
template<class T>
using V = std::vector<T>;

/* using std */
using std::cout;
constexpr char endl = '\n';
using std::cin;
using std::pair;
using std::string;
using std::stack;
using std::queue;
using std::vector;
using std::list;
using std::map;
using std::unordered_map;
using std::multimap;
using std::unordered_multimap;
using std::set;
using std::unordered_set;
using std::unordered_multiset;
using std::multiset;
using std::bitset;
using std::priority_queue;
using std::tuple;

/* constant value */
//constexpr ll MOD = 1000000007;
constexpr ll MOD = 998244353;
//constexpr ll MOD = 2;

/* Initial processing  */
struct Preprocessing { Preprocessing() { std::cin.tie(0); std::ios::sync_with_stdio(0); }; }_Preprocessing;

/* Remove the source of the bug */
inline signed pow(signed, signed) { assert(false); return -1; }

/* define hash */
namespace std {
template <>	class hash<std::pair<ll, ll>> { public:	size_t operator()(const std::pair<ll, ll>& x) const { return hash<ll>()(1000000000 * x.first + x.second); } };
}

/* input */
template<class T> std::istream& operator >> (std::istream& is, vector<T>& vec) { for (T& x : vec) is >> x; return is; }

//=============================================================================================

/**
 *	セグメント木を構成する
 *	2methodの変更により調整
 */
template<class T>
class SegmentTree {
private:
	const T initialValue = T(0);
	const T ignoreValue = T(0);

	const ll m_size;
	vector<T> m_node;

	ll calcSize(ll n) {
		ll size = 1;
		while (size < n) {
			size *= 2;
		}
		return size;
	}

	/**
	 * 値の更新(更新:=, 加算:+=, etc...)
	 */
	void update(ll k, T x) {
		m_node[k] = x;
	}

	/**
	* 値の併合
	*/
	T merge(T xl, T xr) {
		return (xl | xr);
	}
public:
	SegmentTree(ll n) :
		m_size(calcSize(n)),
		m_node(m_size * 2 - 1, initialValue) {}

	void add(ll itr, T val) {
		ll i = itr + m_size - 1;
		update(i, val);

		while (i > 0) {
			i = (i - 1) / 2;
			m_node[i] = merge(m_node[i * 2 + 1], m_node[i * 2 + 2]);
		}
		/**
		cout << "-- tree -- " << endl;
		REP(i, 2 * m_size - 1) {
			cout << m_node[i] << endl;
		}
		/*//**/
	}

	T query(ll a, ll b) { return query(a, b + 1, 0, 0, m_size); }
	T query(ll a, ll b, ll k, ll l, ll r) {
		if (r <= a || b <= l) { return ignoreValue; }
		if (a <= l && r <= b) { return m_node[k]; }
		return merge(
			query(a, b, 2 * k + 1, l, (l + r) / 2),
			query(a, b, 2 * k + 2, (l + r) / 2, r)
		);
	}
};

signed main() {
	ll n;
	string s;
	cin >> n >> s;

	auto tree = SegmentTree<bitset<26>>(n);
	auto ctob = [](char c) {
		ll k = c - 'a';
		auto bit = bitset<26>(0);
		bit[k] = 1;
		return bit;
	};

	REP(i, n) {
		tree.add(i, ctob(s[i]));
	}

	ll q;
	cin >> q;
	REP(_, q) {
		ll p;
		cin >> p;
		if (p == 2) {
			ll l, r;
			cin >> l >> r;
			--l; --r;
			cout << tree.query(l, r).count() << endl;
			continue;
		}

		ll x; char c;
		cin >> x >> c;
		--x;
		tree.add(x, ctob(c));
	}
}


Measured memory_bytes: 9116