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

#define endl '\n'
#define lfs cout<<fixed<<setprecision(10)
#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()
#define spa << " " <<
#define fi first
#define se second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define rep(i,n,m) for(ll i = (n); i < (ll)(m); i++)
#define rrep(i,n,m) for(ll i = (m) - 1; i >= (ll)(n); i--)
using ll = long long;
using ld = long double;
const ll MOD1 = 1e9+7;
const ll MOD9 = 998244353;
const ll INF = 1e18;
using P = pair<ll, ll>;
template<typename T>
bool chmin(T &a,T b){if(a>b){a=b;return true;}else return false;}
template<typename T>
bool chmax(T &a,T b){if(a<b){a=b;return true;}else return false;}
ll median(ll a,ll b, ll c){return a+b+c-max({a,b,c})-min({a,b,c});}
void ans1(bool x){if(x) cout<<"Yes"<<endl;else cout<<"No"<<endl;}
void ans2(bool x){if(x) cout<<"YES"<<endl;else cout<<"NO"<<endl;}
void ans3(bool x){if(x) cout<<"Yay!"<<endl;else cout<<":("<<endl;}
template<typename T1,typename T2>
void ans(bool x,T1 y,T2 z){if(x)cout<<y<<endl;else cout<<z<<endl;}  
template<typename T>
void debug(vector<vector<T>>&v,ll h,ll w){for(ll i=0;i<h;i++)
{cout<<v[i][0];for(ll j=1;j<w;j++)cout spa v[i][j];cout<<endl;}};
void debug(vector<string>&v,ll h,ll w){for(ll i=0;i<h;i++)
{for(ll j=0;j<w;j++)cout<<v[i][j];cout<<endl;}};
template<typename T>
void debug(vector<T>&v,ll n){if(n!=0)cout<<v[0];
for(ll i=1;i<n;i++)cout spa v[i];cout<<endl;};
template<typename T>
vector<vector<T>>vec(ll x, ll y, T w){
  vector<vector<T>>v(x,vector<T>(y,w));return v;}
ll gcd(ll x,ll y){ll r;while(y!=0&&(r=x%y)!=0){x=y;y=r;}return y==0?x:y;}
vector<ll>dx={1,0,-1,0,1,1,-1,-1};
vector<ll>dy={0,1,0,-1,1,-1,1,-1};
template<typename T>
vector<T> make_v(size_t a,T b){return vector<T>(a,b);}
template<typename... Ts>
auto make_v(size_t a,Ts... ts){
  return vector<decltype(make_v(ts...))>(a,make_v(ts...));
}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, pair<T1, T2>&p){
  return os << p.first << " " << p.second;
}  
template<typename T = unsigned int, int size = 30>
struct BinaryTrie{
  struct Node{
    vector<ll>next;
    ll num;
    T val;
    Node():num(0){
      next.assign(2,-1);
    }
  };
  T rev;
  vector<Node>data;
  BinaryTrie(){
    rev = 0;
    data.emplace_back();
  }
  void insert(T x){
    ll pos=0;
    bitset<size>bit(rev^x);
    for(ll i=size-1;i>=0;i--){
      if(data[pos].next[bit[i]]==-1){
        data[pos].next[bit[i]]=data.size();
        data.emplace_back();
      }
      data[pos].num++;
      pos = data[pos].next[bit[i]];
    }
    data[pos].num++;
    data[pos].val=x;
  }
  void erase(T x){
    ll pos=0;
    bitset<size>bit(rev^x);
    for(ll i=size-1;i>=0;i--){
      data[pos].num--;
      pos = data[pos].next[bit[i]];
    }
    data[pos].num--;
  }
  void xor_all(T x){
    rev ^= x;
  }
  T max_element(){
    ll pos=0;
    bitset<size>bit(~rev);
    for(ll i=size-1;i>=0;i--){
      if(data[pos].next[bit[i]] != -1 && data[data[pos].next[bit[i]]].num >= 1){
        pos = data[pos].next[bit[i]];
      }
      else pos = data[pos].next[!bit[i]];
    }
    return data[pos].val ^ rev;
  }
  T min_element(){
    ll pos=0;
    bitset<size>bit(rev);
    for(ll i=size-1;i>=0;i--){
      if(data[pos].next[bit[i]] != -1 && data[data[pos].next[bit[i]]].num >= 1){
        pos = data[pos].next[bit[i]];
      }
      else pos = data[pos].next[!bit[i]];
    }
    return data[pos].val ^ rev;
  }
  T kth_element(ll k){//下からk番目、0-indexed
    ll pos=0;
    bitset<size>bit(rev);
    for(ll i=size-1;i>=0;i--){
      if(data[pos].next[bit[i]] != -1 && data[data[pos].next[bit[i]]].num > k){
        pos = data[pos].next[bit[i]];
      }
      else{
        if(data[pos].next[bit[i]] != -1)k -= data[data[pos].next[bit[i]]].num;
        pos = data[pos].next[!bit[i]];
      }
    }
    return data[pos].val ^ rev;
  }
  ll num_all(){
    return data[0].num;
  }
  ll count_lower(T x){
    ll pos=0,ret=0;
    bitset<size>bit(rev^x);
    for(ll i=size-1;i>=0;i--){
      if(bit[i]&&data[pos].next[!bit[i]] != -1)ret += data[data[pos].next[!bit[i]]].num;
      if(data[pos].next[bit[i]] != -1)pos = data[pos].next[bit[i]];
      else break;
    }
    return ret;
  }
  ll lower_bound(T x){
    ll idx = count_lower(x);
    if(idx == num_all())return -1;
    else return kth_element(idx);
  }
  ll upper_bound(T x){
    return lower_bound(x + 1);
  }
};
int main(){
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ll res=0,buf=0;
  bool judge = true;
  ll n;cin>>n;
  string s;cin>>s;
  vector<BinaryTrie<>>st(26);
  rep(i,0,n)st[s[i]-'a'].insert(i);
  ll q;cin>>q;
  while(q--){
    ll t;cin>>t;
    if(t==1){
      ll x;cin>>x;x--;
      char c;cin>>c;
      st[s[x]-'a'].erase(x);
      st[c-'a'].insert(x);
      s[x]=c;
    }
    else{
      ll l,r;cin>>l>>r;l--;
      ll ret=0;
      rep(i,0,26){
        if(st[i].lower_bound(l)!=-1&&st[i].lower_bound(l)<r)ret++;
      }
      cout<<ret<<endl;
    }
  }
  return 0;
}

Measured memory_bytes: 219512