#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll, ll> P;
typedef vector<ll> VI;
typedef vector<VI> VVI;
const ll MOD = 1000000007;
const ll INF = 2147483647;
const ll LINF = 9223372036854775807;
#define REP(i, n) for (int i = 0; i < n; i++)
#define ALL(v) v.begin(), v.end()

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 F f, const Monoid &M1) : 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 numofbits(ll bits) {
	bits = (bits & 0x55555555) + (bits >> 1 & 0x55555555);
	bits = (bits & 0x33333333) + (bits >> 2 & 0x33333333);
	bits = (bits & 0x0f0f0f0f) + (bits >> 4 & 0x0f0f0f0f);
	bits = (bits & 0x00ff00ff) + (bits >> 8 & 0x00ff00ff);
	return (bits & 0x0000ffff) + (bits >> 16 & 0x0000ffff);
}

int main() {
	int n; cin >> n;
    string s; cin >> s;
    SegmentTree<int> st(n,[](int a, int b) { return (a | b); }, 0);
    REP(i,n){
        st.update(i,1<<(s[i]-'a'));
    }
    int q; cin >> q;
    VI ans(0);
    REP(i,q){
        int a;
        cin >> a;
        if(a == 1){
            int p; char c;
            cin >> p >> c;
            st.update(p-1,1<<(c-'a'));
        }
        else{
            int l, r;
            cin >> l >> r;
            cout << numofbits(st.query(l-1,r)) << endl;
        }
    }
    return 0;
}

Measured memory_bytes: 4996