#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <limits>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <functional>
#include <iomanip>

using namespace std;

#ifdef LOCAL
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define eprintf(...) 42
#endif
using ll = long long;
using vll = std::vector<ll>;
using vvll = std::vector<vll>;
using vvvll = std::vector<vvll>;
#define reps(i, S, E) for (ll i = (S); i <= (E); i++)
#define rep(i, N) reps(i, 0, N-1)
#define deps(i, E, S) for (ll i = (E); i >= (S); i--)
#define dep(i, N) deps(i, N-1, 0)
const ll INF = 1LL << 60;
const int INF_INT = 1 << 30;

template<class T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; }return false; }
template<class T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; }return false; }
struct mll {
	static ll MOD;
	ll val;
	mll(ll v = 0) : val(v % MOD) { if (val < 0) val += MOD; }
	mll operator - () const { return -val; }
	mll operator + (const mll &b) const { return val + b.val; }
	mll operator - (const mll &b) const { return val - b.val; }
	mll operator * (const mll &b) const { return val * b.val; }
	mll operator / (const mll &b) const { return mll(*this) /= b; }
	mll operator + (ll b) const { return *this + mll(b); }
	mll operator - (ll b) const { return *this - mll(b); }
	mll operator * (ll b) const { return *this * mll(b); }
	friend mll operator + (ll a, const mll &b) { return b + a; }
	friend mll operator - (ll a, const mll &b) { return -b + a; }
	friend mll operator * (ll a, const mll &b) { return b * a; }
	mll &operator += (const mll &b) { val = (val + b.val) % MOD; return *this; }
	mll &operator -= (const mll &b) { val = (val + MOD - b.val) % MOD; return *this; }
	mll &operator *= (const mll &b) { val = (val*b.val) % MOD; return *this; }
	mll &operator /= (const mll &b) {
		ll c = b.val, d = MOD, u = 1, v = 0;
		while (d) {
			ll t = c / d;
			c -= t * d; swap(c, d);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	mll &operator += (ll b) { return *this += mll(b); }
	mll &operator -= (ll b) { return *this -= mll(b); }
	mll &operator *= (ll b) { return *this *= mll(b); }
	mll &operator /= (ll b) { return *this /= mll(b); }
	bool operator == (const mll &b) { return val == b.val; }
	bool operator != (const mll &b) { return val != b.val; }
	bool operator == (ll b) { return *this == mll(b); }
	bool operator != (ll b) { return *this != mll(b); }
	friend bool operator == (ll a, const mll &b) { return mll(a) == b.val; }
	friend bool operator != (ll a, const mll &b) { return mll(a) != b.val; }
	friend ostream &operator << (ostream &os, const mll &a) { return os << a.val; }
	friend istream &operator >> (istream &is, mll &a) { return is >> a.val; }
	static mll Combination(ll a, ll b) {
		chmin(b, a - b);
		if (b < 0) return mll(0);
		mll c = 1;
		rep(i, b) c *= a - i;
		rep(i, b) c /= i + 1;
		return c;
	}
};
using vmll = std::vector<mll>;
using vvmll = std::vector<vmll>;
using vvvmll = std::vector<vvmll>;
using vvvvmll = std::vector<vvvmll>;

struct Fast {
	Fast() {
		cin.tie(0);
		ios::sync_with_stdio(false);
		cout << fixed << setprecision(std::numeric_limits<double>::max_digits10);
	}
} fast; //cin,cout高速化のおまじない＋桁数指定

ll mll::MOD = (ll)(1e9 + 7);// 998244353ll;


int N, Q;
struct LazySegmentTree {
private:
	int n;
	vector<ll> node, lazy;

public:
	LazySegmentTree(vector<ll> v) {
		int sz = (int)v.size();
		n = 1; while (n < sz) n *= 2;
		node.resize(2 * n - 1);
		lazy.resize(2 * n - 1, 0);

		for (int i = 0; i < sz; i++) node[i + n - 1] = v[i];
		for (int i = n - 2; i >= 0; i--) node[i] = node[i * 2 + 1] + node[i * 2 + 2];
	}

	void eval(int k, int l, int r) {
		if (lazy[k] != 0) {
			node[k] += lazy[k];
			if (r - l > 1) {
				lazy[2 * k + 1] += lazy[k] / 2;
				lazy[2 * k + 2] += lazy[k] / 2;
			}
			lazy[k] = 0;
		}
	}

	void add(int a, int b, ll x, int k = 0, int l = 0, int r = -1) {
		if (r < 0) r = n;
		eval(k, l, r);
		if (b <= l || r <= a) return;
		if (a <= l && r <= b) {
			lazy[k] += (r - l) * x;
			eval(k, l, r);
		}
		else {
			add(a, b, x, 2 * k + 1, l, (l + r) / 2);
			add(a, b, x, 2 * k + 2, (l + r) / 2, r);
			node[k] = node[2 * k + 1] + node[2 * k + 2];
		}
	}

	ll getsum(int a, int b, int k = 0, int l = 0, int r = -1) {
		if (r < 0) r = n;
		eval(k, l, r);
		if (b <= l || r <= a) return 0;
		if (a <= l && r <= b) return node[k];
		ll vl = getsum(a, b, 2 * k + 1, l, (l + r) / 2);
		ll vr = getsum(a, b, 2 * k + 2, (l + r) / 2, r);
		return vl + vr;
	}
};

int main() {
	ll N;
	cin >> N;
	string S;
	cin >> S;
	ll len_S = S.size();
	ll M;
	cin >> M;
	vector<ll> Q(M);
	vector<ll> A(M);
	vector<ll> B(M);
	rep(i, M) {
		cin >> Q[i] >> A[i];
		A[i]--;

		if (Q[i] == 1) {
			string temp;
			cin >> temp;
			B[i] = temp[0] - 'a';
		}
		else {
			cin >> B[i];
			B[i]--;
		}
			
	}

	vll T(N, 0);
	vector<LazySegmentTree> seg(26, (vector<ll>(N, 0)));
	rep(i, N) {
		T[i] = S[i] - 'a';
		seg[T[i]].add(i, N, 1);
	}

	//cin >> N >> Q;
	//
	//for (int i = 0; i < Q; i++) {
	//	int query; cin >> query;
	//	if (query == 0) {
	//		int s, t, x; cin >> s >> t >> x;
	//		seg.add(s - 1, t, x);
	//	}
	//	else {
	//		int s, t; cin >> s >> t;
	//		cout << seg.getsum(s - 1, t) << endl;
	//	}
	//}

	rep(i, M) {
		if (Q[i] == 1) {
			eprintf("\nQ1:\n");

			//更新
			ll curr = T[A[i]];
			ll update = B[i];
			eprintf("curr:%lld update:%lld\n", curr, update);

			if (curr == update) {
				continue;
			}

			//抜く
			seg[curr].add(A[i], N, -1);

			//足す
			seg[update].add(A[i], N, 1);

			//変更
			T[A[i]] = update;
		}
		else {
			eprintf("\nQ2:\n");

			ll result = 0;

			rep(j, 26) {
				ll sum = seg[j].getsum(B[i], B[i] + 1) - (A[i] == 0 ? 0 : seg[j].getsum(A[i] - 1, A[i]));
				if (sum > 0) {
					result++;
				}

				eprintf("sum[%lld]:%lld ", j, sum);
			}

			cout << result << endl;
		}
	}

	return 0;
}


Measured memory_bytes: 451612