#include<bits/stdc++.h>
using namespace std;
//#include<boost/multiprecision/cpp_int.hpp>
//using boost::multiprecision::cpp_int;

#define int long long
#define cint cpp_int
#define endl "\n"
#define REP(i,a,n) for(int i=a;i<n;++i)
#define REPR(i,a,n) for(int i=a;i>n;--i)
#define RUP(a,b) (((a)+(b)-1)/(b))
#define ALL(v) (v).begin(),(v).end()
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define MOD 1000000007
#define INF LLONG_MAX/2
#define PI acos(-1.0)

typedef long long ll;
typedef pair<int,int> Pii;
typedef tuple<int,int,int> Tiii;
typedef vector<int> Vi;
typedef vector<Vi> VVi;
typedef vector<Pii> VPii;
typedef vector<string> Vs;
typedef priority_queue<int> PQi;

template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
void vout(Vi &v){for(int i=0;i<(v).size();i++) cout<<v[i]<<" ";cout<<endl;}
void vout(Vs &v){for(int i=0;i<(v).size();i++) cout<<v[i]<<" ";cout<<endl;}
void vvout(VVi &v){for(int i=0;i<(v).size();i++) vout(v[i]);}
int gcd(int a,int b){return b?gcd(b,a%b):a;}
int lcm(int a,int b){return a/gcd(a,b)*b;}
int mypow(int x, int n, int m){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 digit(int k,int i){string s = to_string(k);return s[s.size()-i]-'0';}
void uniq(Vi &v){sort(v.begin(),v.end()); v.erase(unique(v.begin(),v.end()),v.end());} //vectorの同じ要素消す
int ctoi(char c){if(c>='0'&&c<='9'){return c-'0';}return 0;}
int leng(int n){string s=to_string(n); return s.size();} //intの桁数
int digitsum(int n){int ret=0; while(n>0){ret+=n%10;n/=10;}return ret;} //桁和
int lesscount(int x,Vi &a){return lower_bound(a.begin(),a.end(),x)-a.begin();} //vector aにおけるx未満の数の個数
int orlesscount(int x,Vi &a){return upper_bound(a.begin(),a.end(),x)-a.begin();} //vector aにおけるx以下の数の個数
int morecount(int x,Vi &a){return a.size()-orlesscount(x,a);} //vector aにおけるxより大きい数の個数
int ormorecount(int x,Vi &a){return a.size()-lesscount(x,a);} //vector aにおけるx以上の数の個数
int count(int x,Vi &a) {return upper_bound(ALL(a),x)-lower_bound(ALL(a),x);} //vector aにおけるxの個数
Vi accum(Vi &v){Vi ret((v).size()+1);REP(i,0,(v).size()) ret[i+1]=ret[i]+v[i];return ret;}
bool comp(Pii a,Pii b){
    if(a.second != b.second) return a.second<b.second;
    else return a.first<b.first;
}

struct SegmentTree {
    int n;
    vector<Vi> node;

    SegmentTree(VVi v){
        int sz = v.size();
        n = 1;
        while(n < sz) n*=2;
        node.resize(2*n-1);
        REP(i,0,node.size()) node[i].resize(26);
        
        REP(i,0,sz) node[i+n-1] = v[i];
        REPR(i,n-2,-1){
            Vi ret(26);
            REP(j,0,26){
                ret[j]=(node[2*i+1][j] | node[2*i+2][j]);
            }
            node[i]=ret;
        }
    }

    void update(int loc, int val) {
        int x = loc+(n-1);
        REP(i,0,node[x].size()) node[x][i]=0;
        node[x][val]=1;
        while(x>0) {
            x = (x-1)/2;
            Vi ret(node[2*x+1].size());
            REP(j,0,node[2*x+1].size()){
                ret[j]=node[2*x+1][j] | node[2*x+2][j];
            }
            node[x]=ret;
        }
    }

    Vi getnum(int a, int b, int k=0, int l=0, int r=-1) {
        if(r < 0) r = n;
        if(r <= a || b <= l){
            Vi ret(26,0);
            return ret;
        }
        if(a <= l && r <= b){
            return node[k];
        }

        Vi vl = getnum(a, b, 2*k+1, l, (l+r)/2);
        Vi vr = getnum(a, b, 2*k+2, (l+r)/2, r);

        Vi ret(26,0);
        REP(j,0,26){
            ret[j]=vl[j] | vr[j];
        }

        return ret;
    }
};

// Generated by 1.1.6 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
signed main(){
    int n;
    string s;
    cin>>n>>s;
    Vi a(n);
    REP(i,0,n) a[i]=s[i]-'a';
    VVi b(n,Vi(26));
    REP(i,0,n){
        b[i][a[i]]++;
    }
//    vvout(b);

    SegmentTree seg(b);

    int q;
    cin>>q;
    REP(i,0,q){
        int type;
        cin>>type;
        if(type==1){
            int i;
            char c;
            cin>>i>>c;
            i--;
            seg.update(i,(int)(c-'a'));
//            vvout(seg.node);
        }else{
            int l,r;
            cin>>l>>r;
            l--;
            Vi ret=seg.getnum(l,r);
            cout<<accumulate(ALL(ret),0)<<endl;
        }
    }


    return 0;
}


Measured memory_bytes: 502788