#include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <cstdio>
#include <cmath>
#include <tuple>
#include <iomanip>
#include <numeric>
#include <unordered_map>
#include <sstream>   
#include<limits.h>
#include<float.h>
#include<list>
#include <array>
#include <complex>
#include<stdio.h>
#include<string.h>
#include <bitset>

using namespace std;
#define int  long long
 
#define I32_MAX 2147483647
#define I64_MAX 9223372036854775807LL
#define I64_MAX2 1223372036854775807LL
#define INF I64_MAX2
#define MOD 1000000007
#define MEM_SIZE 10000
#define DEBUG_OUT true
#define ALL(x) (x).begin(),(x).end()

template<typename T> void DEBUG(T e){if(DEBUG_OUT == false)return; std::cout << e <<" ";}
template<typename T> void DEBUG(const std::vector<T>& v){if(DEBUG_OUT == false)return;for(const auto& e : v){std::cout<< e << " "; } std::cout << std::endl;}
template<typename T> void DEBUG(const std::vector<std::vector<T> >& vv){if(DEBUG_OUT == false)return;for(const auto& v : vv){ DEBUG(v); } }
template<class T,class... Ts> void DEBUG(T d, Ts... e){if(DEBUG_OUT == false)return;DEBUG(d);DEBUG(e...);}
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; exit(0);}}
template< typename T1, typename T2 > inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template< typename T1, typename T2 > inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template <typename X>
struct SegTree {
    using FX = function<X(X, X)>; // X•X -> X となる関数の型
    int n;
    FX fx;
    const X ex;
    vector<X> dat;
    SegTree(int n_, FX fx_, X ex_) : n(), fx(fx_), ex(ex_), dat(n_ * 4, ex_) {
        int x = 1;
        while (n_ > x) {
            x *= 2;
        }
        n = x;
    }
 
    void set(int i, X x) { dat[i + n - 1] = x; }
    void build() {
        for (int k = n - 2; k >= 0; k--) dat[k] = fx(dat[2 * k + 1], dat[2 * k + 2]);
    }
 
    void update(int i, X x) {
        i += n - 1;
        dat[i] = x;
        while (i > 0) {
            i = (i - 1) / 2;  // parent
            dat[i] = fx(dat[i * 2 + 1], dat[i * 2 + 2]);
        }
    }
 
    X query(int a, int b) { return query_sub(a, b, 0, 0, n); }
    X query_sub(int a, int b, int k, int l, int r) {
        if (r <= a || b <= l) {
            return ex;
        } else if (a <= l && r <= b) {
            return dat[k];
        } else {
            X vl = query_sub(a, b, k * 2 + 1, l, (l + r) / 2);
            X vr = query_sub(a, b, k * 2 + 2, (l + r) / 2, r);
            return fx(vl, vr);
        }
    }
};

void solve(void)
{
   int N;
   cin>>N;
   string str;
   cin>>str;
    auto fx = [](int x1, int x2) -> int { return x1|x2; };
    int ex = 0;
    SegTree<int> Seg(N, fx, ex);
    for (int i = 0; i < N; i++)
    {
      int X =(int)(str[i] - 'a');
      Seg.set(i,(1<<X));
    }
    Seg.build();
    int Q;cin>>Q;
    for (int i = 0; i < Q; i++)
    {
      int q;cin>>q;
      if(q == 1)
      {
        int I; char c;
        cin>>I>>c;
        int X =(int)(c - 'a');
        // DEBUG(,"\n");
        Seg.update(I-1,(1<<X));
      }
      else
      {
        int L,R;
        cin>>L>>R;
        L--;
        int X = Seg.query(L,R);
        cout<<__builtin_popcount(X)<<endl;
      }
    }
    
    

  return;
}

int32_t main(int32_t argc, const char *argv[])
{
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  std::cout << std::fixed;
  std::cout << std::setprecision(9);
  solve();

  return 0;
}


Measured memory_bytes: 16540