#include <bits/stdc++.h>
 
//#include <unistd.h>
//#include <iostream>
 
using namespace std;
 
#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl;
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}
typedef long long ll;
//#define int ll
 
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const long double pi = 3.1415926535897932384626433832795028841971L;
#define Sp(p) cout<<setprecision(25)<< fixed<<p<<endl;
//int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
//int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
vi dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};
vi dx2 = { 1,1,0,-1,-1,-1,0,1 }, dy2 = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
const ll MOD = 1000000007;
//const ll MOD = 998244353;
// #define mp make_pair
//#define endl '\n'

template <typename T>
class SegmentTree {
public:
  using F = function<T(T&, T&)>;
  int n;
  vector<T > dat;
  T e; // �P�ʌ�
  F query_func;
  F update_func;
  
  SegmentTree(vector<T> a, F query_func, F update_func, T e) :n(a.size()), query_func(query_func), update_func(update_func), e(e) {
	dat.resize(4 * n);
	init(0, 0, n, a);
  }

  void init(int k, int l, int r, vector<T> &a) {
	if (r - l == 1) {
	  dat[k] = a[l];
	}
	else {
	  int lch = 2 * k + 1, rch = 2 * k + 2;
	  init(lch, l, (l + r) / 2, a);
	  init(rch, (l + r) / 2, r, a);
	  dat[k] = query_func(dat[lch], dat[rch]);
	}
  }

  //k�Ԗڂ̒l��a�ɕύX
  void update(int k, T a, int v, int l, int r) {
	if (r - l == 1) {
	  dat[v] = update_func(dat[v], a);
	}
	else {
	  if (k < (l + r) / 2)
		update(k, a, 2 * v + 1, l, (l + r) / 2);
	  else {
		update(k, a, 2 * v + 2, (l + r) / 2, r);
	  }
	  dat[v] = query_func(dat[v * 2 + 1], dat[v * 2 + 2]);
	}
  }
	

  //[a,b)�̍ŏ��l�����߂�
  //���̂ق��̈����͌v�Z�̊ȒP�̂��߂̈���
  //k�͐ړ_�̔ԍ�,l,r�͂��̐ړ_��[l,r)�ɑΉ����Ă��邱�Ƃ�\��
  //�]���āA�O�����query(a,b,0,0,n)�Ƃ��Ă��
  T query(int a, int b, int k, int l, int r) {
	if (r <= a || b <= l) {
	  return e;
	}
	if (a <= l && r <= b) {
	  return dat[k];
	}
	else {
	  T ul = query(a, b, k * 2 + 1, l, (l + r) / 2);
	  T ur = query(a, b, k * 2 + 2, (l + r) / 2, r);
	  return query_func(ul, ur);
	}
  }

  // �����𖞂����ĉE��T��
  int find(int a, int b, int k, int l, int r, int x) {
	// �����𒼂�
	if (dat[k] < x || r <= a || b <= l) return -1;
	if (l + 1 == r) {
	  // �����𒼂�
	  if (dat[k] >= x) return l;
	  else return -1;
	}
	int rv = find(a, b, 2 * k + 2, (l + r) / 2, r, x);
	if (rv != -1) return rv;
	return find(a, b, 2 * k + 1, l, (l + r) / 2, x);
  }
};

vi f(vi a, vi b) {return b;}
vi g(vi a, vi b) {
	vi res(26);
	rep (i, 26) res[i] = a[i] + b[i];
	return res;
}

signed main() {
	fio();
	int n;
	cin >> n;
	string s;
	cin >> s;

	vii a(n, vi(26));
	rep (i, n) {
		a[i][s[i] - 'a']++;
	}


	SegmentTree<vi> seg(a, g, f, vi(26));
	int q;
	cin >> q;
	while (q--) {
		int t;
		cin >> t;
		if (t == 1) {
			int i;
			char c;
			cin >> i >> c;
			i--;
			vi temp(26);
			temp[c - 'a'] = 1;
			seg.update(i, temp, 0, 0, seg.n);
		}
		else {
			int l, r;
			cin >> l >> r;
			l--;
			vi res = seg.query(l, r, 0, 0, seg.n);
			//DEBUG_VEC(res);
			int ans = 0;
			rep (i, 26) {
				if (res[i] > 0) ans++;
			}
			cout << ans << endl;
		}
	}
}

Measured memory_bytes: 289820