#include <bits/stdc++.h>
using namespace std;
#define __ <<" "<<
#define ___ <<" "
#define bash push_back
#define ALL(x) x.begin(),x.end()
//#define int long long

struct IoSetup {
    IoSetup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout <<fixed<<setprecision(12);
        cerr <<fixed<<setprecision(12);
    }
}IoSetup;

typedef long long ll;
typedef pair < int , int >  pii;
static constexpr const signed int INF = 0x3f3f3f3f;
static constexpr const signed long long LINF = 0x3f3f3f3f3f3f3f3fLL;
static constexpr const signed int SMOD = 1000000007;
static constexpr const signed int NMOD = 998244353;
static constexpr const signed int dx[]={1,0,-1,0,1,1,-1,-1};
static constexpr const signed int dy[]={0,-1,0,1,-1,1,-1,1};

inline bool inside(int x,int y,int w,int h){return (x>=0 && y>=0 && x<w && y<h);}
template<class T>bool chmax(T &a, const T &b){return(a=max(a,b))==b;}
template<class T>bool chmin(T &a, const T &b){return(a=min(a,b))==b;}
inline int qp(int a,ll b,int mo){int ans=1;do{if(b&1)ans=1ll*ans*a%mo;a=1ll*a*a%mo;}while(b>>=1);return ans;}

template< typename Monoid >
struct SegmentTree {
    using F = function< Monoid(Monoid, Monoid) >;

    int sz;
    vector< Monoid > seg;

    const F f;
    const Monoid M1;

    SegmentTree(int n, const Monoid &M1, const F f) : f(f), M1(M1) {
        sz = 1;
        while(sz < n) sz <<= 1;
        seg.assign(2 * sz, M1);
    }

    void set(int k, const Monoid &x) {
        seg[k + sz] = x;
    }

    void build() {
        for(int k = sz - 1; k > 0; k--) {
            seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
        }
    }

    void update(int k, const Monoid &x) {
        k += sz;
        seg[k] = x;
        while(k >>= 1) {
            seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
        }
    }

    Monoid query(int a, int b) {
        Monoid L = M1, R = M1;
        for(a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
            if(a & 1) L = f(L, seg[a++]);
            if(b & 1) R = f(seg[--b], R);
        }
        return f(L, R);
    }

    Monoid operator[](const int &k) const {
        return seg[k + sz];
    }

    template< typename C >
    int find_subtree(int a, const C &check, Monoid &M, bool type) {
        while(a < sz) {
            Monoid nxt = type ? f(seg[2 * a + type], M) : f(M, seg[2 * a + type]);
            if(check(nxt)) a = 2 * a + type;
            else M = nxt, a = 2 * a + 1 - type;
        }
        return a - sz;
    }


    template< typename C >
    int find_first(int a, const C &check) {
        Monoid L = M1;
        if(a <= 0) {
            if(check(f(L, seg[1]))) return find_subtree(1, check, L, false);
            return -1;
        }
        int b = sz;
        for(a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
            if(a & 1) {
                Monoid nxt = f(L, seg[a]);
                if(check(nxt)) return find_subtree(a, check, L, false);
                L = nxt;
                ++a;
            }
        }
        return -1;
    }

    template< typename C >
    int find_last(int b, const C &check) {
        Monoid R = M1;
        if(b >= sz) {
            if(check(f(seg[1], R))) return find_subtree(1, check, R, true);
            return -1;
        }
        int a = sz;
        for(b += sz; a < b; a >>= 1, b >>= 1) {
            if(b & 1) {
                Monoid nxt = f(seg[--b], R);
                if(check(nxt)) return find_subtree(b, check, R, true);
                R = nxt;
            }
        }
        return -1;
    }
};

int n, q;
string s;



signed main() {

    cin >> n >> s >> q;

    SegmentTree<int> seg(n, 0, [](int a, int b) { return a | b;});

    int bits[200];

    for(int i = 0, s = 1; i < 26; i++, s<<=1) {
        bits[i+'a'] = s;
    }

    for(int i = 0; i < n; i++) {
        seg.set(i, bits[s[i]]);
    }

    seg.build();

    int a, b;
    for(int i = 0; i < q; i++) {
        cin >> a >> b;

        if(a == 1) {
            char c;
            cin >> c;
            seg.update(b-1, bits[c]);
        }
        else {
            int c;
            cin >> c;
            cout << __builtin_popcount(seg.query(b-1, c)) << endl;
        }
    }

    
  
    return 0;
}



Measured memory_bytes: 5148