/*                         _
                        _ooOoo_
                       o8888888o
                       88" . "88
                       (| -_- |)
                       O\  =  /O
                    ____/`---'\____
                  .'  \\|     |//  `.
                 /  \\|||  :  |||//  \
                /  _||||| -:- |||||_  \
                |   | \\\  -  /'| |   |
                | \_|  `\`---'//  |_/ |
                \  .-\__ `-. -'__/-.  /
              ___`. .'  /--.--\  `. .'___
           ."" '<  `.___\_<|>_/___.' _> \"".
          | | :  `- \`. ;`. _/; .'/ /  .' ; |
          \  \ `-.   \_\_`. _.'_/_/  -' _.' /
===========`-.`___`-.__\ \___  /__.-'_.'_.-'================

                  Please give me AC.
*/

#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <numeric>
#include <string>
#include <sstream>
#include <complex>
#include <bitset>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <deque>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <chrono>
#include <random>

using namespace std;

using int64 = long long;
using uint64 = unsigned long long;
using vi = vector<int>;
using vl = vector<int64>;
using pii = pair<int, int>;
using pll = pair<int64, int64>;

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define all(v) (v).begin(), (v).end()
#define print(x) cout << (x) << '\n'
#define print2(x, y) cout << (x) << ' ' << (y) << '\n'
#define print3(x, y, z) cout << (x) << ' ' << (y) << ' ' << (z) << '\n'
#define printn(v) rep(i, (v).size() - 1) cout << (v)[i] << ' '; cout << (v)[n - 1] << '\n';
#define debug(x) cerr << #x << ": " << (x) << '\n'
#define debug2(x, y) cerr << #x << ": " << (x) << ", " << #y << ": " << (y) << '\n'
#define debug3(x, y, z) cerr << #x << ": " << (x) << ", " << #y << ": " << (y) << ", " << #z << ": " << (z) << '\n'
#define dbg(v) for (size_t _ = 0; _ < v.size(); ++_){cerr << #v << "[" << _ << "] : " << v[_] << '\n';}
// constant
const int INF = (1<<30) - 1;
const int64 INF64 = (1LL<<62) - 1;

template<typename T> T gcd(T a, T b) {
    if (a < b) return gcd(b, a);
    T r;
    while ((r = a % b)) {
        a = b;
        b = r;
    }
    return b;
}

template<typename T> T lcm(const T a, const T b) {
    return a / gcd(a, b) * b;
}

template<typename T> bool chmin(T& a, const T& b) {
    if (a > b) return a = b, true; else return false;
}

template<typename T> bool chmax(T& a, const T& b) {
    if (a < b) return a = b, true; else return false;
}

// End of template.
// begin monoid
template<typename T, T f_(T const, T const)>
class Monoid {
public:
    using type = T;

    static T f(T const a, T const b) {
        return f_(a, b);
    }

    static const T unit;

    template<typename I>
    static T concat(I const& begin, I const& end) {
        return accumulate(begin, end, unit, f);
    }

    static T pow(T base, int exp) {
        T res = unit;
        while (exp > 0) {
            if (exp & 1) res = f(base, res);
            base = f(base, base);
            exp >>= 1;
        }
        return res;
    }
};
// end monoid


// begin segment_tree
// monoid に依存
template<typename M>
typename M::type st_default(typename M::type const m, typename M::type const op, int const b) {
    return M::f(m, op);
}

/*
 * セグメントツリー
 */
template<typename M>
class SegmentTree {
public:
    using MT = typename M::type;
    SegmentTree(const int n) {
        depth = int (ceil(log2(max(2, n))));
        this->n = 1 << depth;
        v.resize(2 * this->n, M::unit);
    }
    void set(int i, MT const m) {
        i += n;
        v[i] = m;
        build(i, i + 1);
    }
    void set(int l, int r, MT const m) {
        l += n; r += n;
        for (int i = l; i < r; ++i) v[i] = m;
        build(l, r);
    }
    template<typename I>
    void set(int l, int r, I it) {
        l += n; r += n;
        for (int i = l; i < r; ++i) v[i] = *it++;
        build(l, r);
    }
    MT get() const {
        return v[1];
    }
    MT get(int const i) {
        return v[n + i];
    }
    MT get(int l, int r) {
        MT L = M::unit, R = M::unit;
        for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
            if (l & 1) L = M::f(L, v[l++]);
            if (r & 1) R = M::f(v[--r], R);
        }
        return M::f(L, R);
    }

    void build(int l, int r) {
        r--;
        l >>= 1; r >>= 1;
        while (l > 0) {
            for (int i = l; i <= r; ++i) v[i] = M::f(v[2 * i], v[2 * i + 1]);
            l >>= 1; r >>= 1;
        }
    }
    
    vector<MT> v;
    int n;
    int depth;
};
// end segment_tree
// begin fast io

char buf[10000000];
int bufi = 0;

template<typename T>
void readui(T &n) {
    n = 0;
    int c = buf[bufi++];
    for (; '0' <= c && c <= '9'; c = buf[bufi++])
        n = 10 * n + c - '0';
}

template<typename T>
void readi(T &n) {
    bool negative = false;
    if (buf[bufi] == '-') negative = true, bufi++;
    readui(n);
    if (negative) n = -n;
}

template<typename T>
void readuf(T &x) {
    x = 0;
    T y = 0;
    int z = 0;
    int c = buf[bufi++];
    for (; '0' <= c && c <= '9'; c = buf[bufi++])
        x = 10 * x + c - '0';
    if (buf[bufi - 1] == '.')
        for (; '0' <= c && c <= '9'; c = buf[bufi++], ++z)
            y = 10 * y + c - '0';
    x += y / pow(10, z);
}

template<typename T>
void readf(T &x) {
    bool negative = false;
    if (buf[bufi] == '-') negative = true, bufi++;
    readuf(x);
    if (negative) x = -x;
}

void reads(string &s) {
    const int begin = bufi;
    int c;
    while (c = buf[bufi++], c != ' ' && c != '\n') {}
    s = string(buf + begin, buf + bufi);
}

void readline(string &s) {
    const int begin = bufi;
    while (buf[bufi++] != '\n') {}
    s = string(buf + begin, buf + bufi);
}

// end fast io



int f(int a, int b) { return a | b; }
using M = Monoid<int, f>;
template<> int const Monoid<int, f>::unit(0);

int main() {
    cout << fixed << setprecision(15);
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin.read(buf, sizeof buf); // 注意: ./a.out < in か pbp | ./a.out で入力すること

    int n, q;
    string s;
    readui(n);
    readline(s);
    readui(q);
    SegmentTree<M> seg(n);
    rep(i, n) {
        seg.v[i + seg.n] = 1 << (s[i] - 'a');
    }
    seg.build(seg.n, 2*seg.n);

    rep(i, q) {
        int t, a, b;
        char c;
        readui(t);
        if (t == 1) {
            readui(a), c = buf[bufi], bufi += 2;
            seg.set(a - 1, 1 << (c - 'a'));
        } else {
            readui(a), readui(b);
            print(__builtin_popcount(seg.get(a - 1, b)));
        }
    }

    return 0;
}



Measured memory_bytes: 5632