#define LOCAL
#define _USE_MATH_DEFINES
#include <array>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
#include <vector>
#include <queue>
#include <stack>
#include <list>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <algorithm>
#include <complex>
#include <cmath>
#include <numeric>
#include <bitset>
#include <functional>
#include <random>
#include <ctime>

using namespace std;

template <typename A, typename B>
ostream& operator <<(ostream& out, const pair<A, B>& a) {
  out << "(" << a.first << "," << a.second << ")";
  return out;
}
template <typename T, size_t N>
ostream& operator <<(ostream& out, const array<T, N>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T>
ostream& operator <<(ostream& out, const vector<T>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T, class Cmp>
ostream& operator <<(ostream& out, const set<T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "}";
  return out;
}
template <typename U, typename T, class Cmp>
ostream& operator <<(ostream& out, const map<U, T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& p : a) { out << (first ? "" : ", "); out << p.first << ":" << p.second; first = 0;} out << "}";
  return out;
}
#ifdef LOCAL
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
#else
#define trace(...) 42
#endif
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cerr << name << ": " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << ": " << arg1 << " |";
  __f(comma + 1, args...);
}

typedef long long int64;
typedef pair<int, int> ii;
const int INF = 1 << 29;
const int MOD = 1e9 + 7;
mt19937 mrand(random_device{}());
int rnd(int x) { return mrand() % x; }

struct fast_ios {
  fast_ios() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
  };
} fast_ios_;

const int N = 5e5 + 10;
char s[N];

template<typename T, size_t N>
struct fenwick {
  T c[N + 1];
  void add(int x, T y) {
    for (; x <= N; x += x & -x) {
      c[x] += y;
    }
  }
  T query(int x) {
    T ret = 0;
    for (; x; x -= x & -x) {
      ret += c[x];
    }
    return ret;
  }
};

fenwick<int, N> c[26];
int main() {
  int n, m;
  scanf("%d%s%d", &n, s, &m);
  for (int i = 0; i < n; ++i) {
    int k = s[i] - 'a';
    c[k].add(i + 1, 1);
  }
  while (m--) {
    int t, x, y;
    static char str[10];
    scanf("%d", &t);
    if (t == 1) {
      scanf("%d%s", &x, str);
      --x;
      y = str[0] - 'a';
      int k = s[x] - 'a';
      c[k].add(x + 1, -1);
      c[y].add(x + 1, 1);
      s[x] = (char)('a' + y);
    } else {
      scanf("%d%d", &x, &y);
      int ret = 0;
      for (int k = 0; k < 26; ++k) {
        ret += c[k].query(y) - c[k].query(x - 1) > 0;
      }
      printf("%d\n", ret);
    }
  }
  return 0;
}


Measured memory_bytes: 54504