#include <bits/stdc++.h> // ver2.4.6
//#include <complex.h> // FFT用
//#include <boost/math/tools/minima.hpp>
//#include <boost/multiprecision/cpp_int.hpp>
//using boost::math::tools::brent_find_minima;//fmin(f,L,R,100)で最小値をmp(x,min)で取得
//using boost::multiprecision::cpp_int; // cpp_int (任意の長さのint)
#define fmin brent_find_minima
#define int long long
#define endl "\n"
#define ALL(v) (v).begin(),(v).end()
#define Vi vector<int>
#define VVi vector<Vi>
#define VVVi vector<VVi>
#define Vm vector<mint>
#define Vs vector<string>
#define Pii pair<int,int>
#define Pdd pair<double,double>
#define VPii vector<Pii>
#define Tiii tuple<int,int,int>
#define VTiii vector<Tiii>
#define PQi priority_queue<int>
#define PQir priority_queue<int,vector<int>,greater<int>>
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define itos to_string
#define stoi stoll
#define FI first
#define SE second
#define cYES cout<<"YES"<<endl
#define cNO cout<<"NO"<<endl
#define cYes cout<<"Yes"<<endl
#define cNo cout<<"No"<<endl
#define cyes cout<<"yes"<<endl
#define cno cout<<"no"<<endl
#define sortr(v) sort(v,greater<>())
#define rep(i,a,b) for(int i=a;i<b;i++)
#define repeq(i,a,b) for(int i=a;i<=b;i++)
#define repreq(i,a,b) for(int i=a;i>=b;i--)
#define dem(a,b) ((a+b-1)/(b))
#define Vin(a) rep(iI,0,a.size())cin>>a[iI]
#define INF 3000000000000000000  //  3.0*10^18(MAXの1/3くらい)
#define MAX LLONG_MAX
#define PI 3.141592653589793238462
#define MOD 1000000007  //  10^9 + 7

using namespace std;

/* デバッグ用 */
void Vout(auto a){if(a.size()==0) cout<<"."<<endl;
else{rep(i,0,a.size()-1)cout<<a[i]<<' ';if(a.size()>0)cout<<a.back()<<endl;}return;}
void Verr(auto a){if(a.size()==0) cerr<<"."<<endl;
else{rep(i,0,a.size()-1)cerr<<a[i]<<' ';if(a.size()>0)cerr<<a.back()<<endl;}return;}
void VVout(auto a){if(a.size()==0)cout<<"."<<endl;
else{rep(i,0,a.size())Vout(a[i]);}return;}
void VVerr(auto a){if(a.size()==0)cerr<<"."<<endl;
else{rep(i,0,a.size())Verr(a[i]);}return;}
void VPout(auto a){if(a.size()==0)cout<<"."<<endl;
else{rep(i,0,a.size())cout<<a[i].FI<<' '<<a[i].SE<<endl;}return;}
void VPerr(auto a){if(a.size()==0)cerr<<"."<<endl;
else{rep(i,0,a.size())cerr<<a[i].FI<<' '<<a[i].SE<<endl;}return;}

/* 便利関数 */
int gcd(int a,int b){return b?gcd(b,a%b):a;} // 最大公約数gcd
int lcm(int a,int b){return a/gcd(a,b)*b;} // 最小公倍数lcm
int mypow(int x, int n, int m){ // 累乗x^n(mod m) O(log(n))
if(n==0)return 1;if(n%2==0)return mypow(x*x%m,n/2,m);else return x*mypow(x,n-1,m)%m;}
int scomb(int n, int r){if(r<0||r>n)return 0;if((n-r)<r)r=n-r; // nCr
int a=1;for(int i=n;i>n-r;--i){a=a*i;}for(int i=1;i<r+1;++i){a=a/i;}return a;}
int comb(int n, int r){if(r<0||r>n)return 0;if((n-r)<r)r=n-r; // nCr(%MOD)
int a=1;for(int i=n;i>n-r;--i){a=a*i%MOD;}for(int i=1;
i<r+1;++i){a=a*mypow(i,MOD-2,MOD)%MOD;}return a%MOD;}
Vi vis(Vi &v){Vi S(v.size()+1);rep(i,1,S.size())S[i]+=v[i-1]+S[i-1];return S;} // 累積和
int digit(int k,int i){string s = itos(k);return s[s.size()-i]-'0';} // i桁目の数字
void press(auto &v){v.erase(unique(ALL(v)),v.end());} // 圧縮
Vi zip(Vi b){int Z=b.size(); // 座標圧縮
Pii p[Z+10];int a=b.size();Vi l(a);for(int i=0;i<a;i++)
p[i]=mp(b[i],i);sort(p,p+a);int w=0;for(int i=0;i<a;i++)
{if(i&&p[i].first!=p[i-1].first)w++;l[p[i].second]=w;}return l;}
Vi beki2V(){Vi a(63);int q = 1;rep(i,0,63){a[i]=q;q*=2;}return a;}
Vi beki2 = beki2V(); // 2^n配列
int modiv(int a,int b){return a*mypow(b,MOD-2,MOD)%MOD;} // a÷b(MOD環境)
int SMALLER(Vi &a,int x){return lower_bound(a.begin(),a.end(),x)-a.begin();}
int orSMALLER(Vi &a,int x){return upper_bound(a.begin(),a.end(),x)-a.begin();}
int BIGGER(Vi &a,int x){return a.size()-orSMALLER(a,x);}
int orBIGGER(Vi &a,int x){return a.size()-SMALLER(a,x);}
int COUNT(Vi &a,int x) {return upper_bound(ALL(a),x)-lower_bound(ALL(a),x);}
int maxind(Vi &a){return max_element(ALL(a))-a.begin();}
int minind(Vi &a){return min_element(ALL(a))-a.begin();}
Vi stpowV(){Vi a(100005);
a[0]=1;repeq(i,1,100004)a[i]=a[i-1]*i%MOD;return a;}
struct mint { // 出力するときだけ.xをつける
  int x;
  mint(int x=0):x((x%MOD+MOD)%MOD){}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= MOD) x -= MOD;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += MOD-a.x) >= MOD) x -= MOD;
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res+=a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res-=a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res*=a;
  }
  mint pow(int t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }
  mint inv() const {
    return pow(MOD-2);
  }
  mint& operator/=(const mint a) {
    return (*this) *= a.inv();
  }
  mint operator/(const mint a) const {
    mint res(*this);
    return res/=a;
  }
};
bool check(int mid){  // ([...,0,0,0,"1",1,1,...])
  int ans = 573;
  if(mid >= ans) return true;
  else return false;
}
 
int binary(){
  int L = 0,R = 1000000010;  //  [L,R]の範囲内に解
  int mid = (L+R)/2;
  
  while(L<R){
    if(check(mid)) {
      R = mid;
    }
    else {
      L = mid+1;
    }
    mid = (L+R)/2;
  }
  
  return mid;
}
//Vi stpow = stpowV(); // 階乗配列(%MOD)


struct UnionFind {
  
  vector<int> par;
  vector<int> siz;
  
  UnionFind(int N) : par(N) { //最初は全てが根であるとして初期化
    for(int i = 0; i < N; i++) par[i] = i;
    siz = Vi(N,1);
  }

  int root(int x) { // データxが属する木の根を再帰で得る：root(x) = {xの木の根}
    if (par[x] == x) return x;
    return par[x] = root(par[x]);
  }

  void unite(int x, int y) { // xとyの木を併合
    int rx = root(x);
    int ry = root(y);
    if (rx == ry) return;
    if (siz[rx] < siz[ry]) swap(rx, ry);
    siz[rx] += siz[ry];
    par[ry] = rx;
  }

  bool same(int x, int y) { // 2つのデータx, yが属する木が同じならtrueを返す
    int rx = root(x);
    int ry = root(y);
    return rx == ry;
  }
  
  int size(int x) { // 素集合のサイズ
    return siz[root(x)];
  }
};

struct RSUQ {
  
  vector<int> data;
  vector<int> bucket1;
  vector<int> bucket2;
  int sq;
  
  RSUQ(int n) {
    sq = sqrt(n);
    if(sq*sq==n) sq--;
    sq++;
    data = Vi(sq*sq,0);
    bucket1 = Vi(sq,-INF); // 1はRUQ成分(-INF)
    bucket2 = Vi(sq,0); // 2はRSQ成分(0)
  }
  
  void rupdate(int L,int R,int k) { // [L,R]は範囲
     R++;
     int dL,dR;
     
     rep(i,0,sq+1) {
       dL = i*sq,dR = (i+1)*sq; // [dL,dR]は小範囲(バケット)
       
       if(dR <= L || R <= dL) continue; // 小範囲が完全に範囲外
       
       if(L <= dL && dR <= R) { // 小範囲が完全に範囲内
         bucket1[i] = k;
       }
       
       else { // 小範囲が範囲と一部重なる
         
         int minn = k;
         
         if(bucket1[i]!=-INF){
           rep(j,dL,dR) {
             data[j] = bucket1[i];
           }
           bucket1[i] = -INF;
         }
         
         rep(j,max(L,dL),min(R,dR)) {
           data[j] = k;
         }
         
         int sum = 0;
         rep(j,dL,dR) {
           sum += data[j];
         }
         bucket2[i] = sum;
         
       }
     }
   }
  
  void update(int i,int k) {
    rupdate(i,i,k);
  }
  
  int rsum(int L,int R) {
     R++;
     int sum = 0;
     int dL,dR;
     
     rep(i,0,sq+1) {
       dL = i*sq,dR = (i+1)*sq; // [dL,dR]は小範囲
       
       if(dR <= L || R <= dL) continue; // 小範囲が完全に範囲外
       
       if(L <= dL && dR <= R) { // 小範囲が完全に範囲内
         if(bucket1[i]!=-INF) sum += bucket1[i]*sq;
         else sum += bucket2[i];
       }
       
       else { // 小範囲が範囲と一部重なる
         rep(j,max(L,dL),min(R,dR)) {
           if(bucket1[i] == -INF) sum += data[j];
           else sum += bucket1[i];
         }
       }
     }
     return sum;
   }
  
  int at(int i) {
    int ib = i/sq;
    if(bucket1[ib]==-INF) return data[i];
    else return bucket1[ib];
  }
  
  void debug() {
    Verr(data);
    Verr(bucket1);
    Verr(bucket2);
    cerr << endl;
  }
  
};

/*　使い方まとめ(0-index)　*/
  
  /*
  
  RSUQ myvec(n) // 宣言 nは必要な要素数
  myvec.at(i) // 配列のi番目にアクセス
  myvec.rupdate(L,R,k) // 配列のL番目からR番目までをkにする
  myvec.update(i,k) // 配列のi番目をkにする
  myvec.rsum(i,j) // 配列の[i,j]の範囲の和を返す
  
  myvec.debug() // 元データ配列とバケット配列を標準エラー出力
  
  */

signed main() {
  cin.tie(0);cout.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(12);
  int n,Q;
  string s;
  cin >> n >> s >> Q;
  
  vector<RSUQ> my(26,RSUQ(n));
  
  rep(i,0,n){
    char c = s[i];
    int now = c-'a';
    my[now].update(i,1);
  }
  
  rep(QW,0,Q){
    int qw;
    cin >> qw;
    if(qw==1){
      int er;
      char c;
      cin >> er >> c;
      er--;
      rep(i,0,26) my[i].update(er,0);
      my[c-'a'].update(er,1);
    }
    else {
      int er,ty;
      cin >> er >> ty;
      er--,ty--;
      int ans = 0;
      rep(i,0,26){
        if(my[i].rsum(er,ty)) ans++;
      }
      cout << ans << endl;
    }
  }
  
  return 0;
}


Measured memory_bytes: 106908