/*
Author : N_o_o_B
Created : March 01 2020 18:13:44 
*/
#include <bits/stdc++.h>
using namespace std;
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
*/
#define TRACE
#ifdef TRACE
#define trace(...) { cerr<<"[ "; __trace__(#__VA_ARGS__, __VA_ARGS__);}
#undef endl
template <typename Arg1,typename Arg2>
ostream& operator << (ostream& out, const pair<Arg1,Arg2> &x) {
    return out<<"("<<x.first<<","<<x.second<<")";
}
 
template <typename Arg1>
ostream& operator << (ostream& out, const vector<Arg1> &a) {
    out<<"[";for(const auto &x:a)out<<x<<",";return out<<"]";
}
 
template <typename Arg1>
ostream& operator << (ostream& out, const set<Arg1> &a) {
    out<<"[";for(const auto &x:a)out<<x<<",";return out<<"]";
}
 
template <typename Arg1,typename Arg2>
ostream& operator << (ostream& out, const map<Arg1,Arg2> &a) {
    out<<"[";for(const auto &x:a)out<<x<<",";return out<<"]";
}
 
template <typename Arg1>
void __trace__(const string name, Arg1&& arg1){
    cerr << name << " : " << arg1 << " ] " << endl;
}
 
template <typename Arg1, typename... Args>
void __trace__(const string names, Arg1&& arg1, Args&&... args){
    const string name = names.substr(0,names.find(','));
    cerr<<name<<" : "<<arg1<<" | ";
    __trace__(names.substr(1+(int)name.size()), args...);
}
#else
    #define trace(args...)
#endif
 
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pair<int,int>> vii;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<pair<ll,ll>> vll;
typedef vector<vl> vvl;
//typedef tree<pii, null_type, less<pii>, rb_tree_tag, tree_order_statistics_node_update> oset;
#define fori(i,n) for(int i=0;i<n;i++)
#define rep(i,a,b) for(int i=a;i<=b;i++)
#define repd(i,a,b) for(int i=a;i>=b;i--)
#define ford(i,n)  for(int i=n-1;i>=0;i--)
#define trav(x,a) for(auto& x:a)
#define all(x) x.begin(),x.end()
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define fi first
#define se second
clock_t time_p=clock();
void time_taken()
{
    time_p=clock()-time_p;
    cerr<<"Time Taken : "<<(float)(time_p)/CLOCKS_PER_SEC<<"\n";
}
//const ll mod=998244353;
const ll mod=1e9+7;
const ll INF=1e18;
const int MAXN = 5e5+5;
struct BIT{
    ll bit[MAXN+1];
    void init(){
        fori(i,MAXN+1) bit[i]=0;
    }
    void update(int x,int v){
        while(x <= MAXN){
            //trace(x);
            bit[x] += v;
            x += (x & -x);
        }
    }
    long long query(int x){
        long long sum = 0;
        while(x > 0){
            sum += bit[x];
            x -= (x & -x);
        }
        return sum;
    }
    void upd_range(int l,int r,int v){
        update(l,v);
        update(r+1,-v);
    }
    long long query_range(int l,int r){
        return query(r) - query(l-1);
    }
}b[26];
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    cout.precision(12);cout << fixed;

    fori(i,26) b[i].init();
    int n;
    cin >> n;
    char s[n+1];
    rep(i,1,n) cin >> s[i];
    rep(i,1,n){
       // trace(i);
        b[s[i]-'a'].update(i,1);
        // cout << "Hi" << endl;
        // cout << flush;
    }
   
    int q;
    cin >> q;
    
    while(q--){
        int t;
        cin >> t;
        if(t==1){
            int i;char c;
            cin >> i >> c;
            b[s[i]-'a'].update(i,-1);
            s[i] = c;
            b[s[i]-'a'].update(i,1);
        }
        else{
            int l,r;
            cin >> l >> r;
            int ans = 0;
            fori(i,26){
                ans += (b[i].query_range(l,r)!=0);
            }
            cout << ans << endl;
        }
    }


    time_taken();
    return 0;
}

Measured memory_bytes: 102400