using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using static System.Console;
using static System.Math;
using static MyIO;
using static MyUtil;
using static BinaryRepresentation;

public class E
{
	public static void Main() => (new Solver()).Solve();
}

public class Solver
{
	public void Solve()
	{
		int N = GetInt();
		string S = GetString();
		var st = new SegmentTree<int>(N, 0, (x, y) => x | y);
		for(int i = 0; i < N; i++)
			st.Update(i, 1 << ((int)(S[i] - 'a')));

		var ans = new List<int>();
		int Q = GetInt();
		for(int i = 0; i < Q; i++)
		{
			switch(GetInt())
			{
				case 1:
					int pos = GetInt() - 1;
					char c = GetChar();
					st.Update(pos, 1 << ((int)(c - 'a')));
					break;

				case 2:
					int l = GetInt() - 1;
					int r = GetInt() - 1;
					ans.Add(popcnt(st.Query(l, r + 1)));
					break;
			}
		}
		WriteLine(string.Join("\n", ans));
	}
}

public class SegmentTree<T>
{
	private int N;
	private T INI;
	private Func<T, T, T> Func;
	private T[] dat;

	public SegmentTree(int n, T ini, Func<T, T, T> func)
	{
		N = 1;		
		while(N < n)
			N <<= 1;

		INI = ini;
		Func = func;
			
		dat = new T[2 * N - 1];
		for(int i = 0; i < 2 * N - 1; i++)
			dat[i] = INI;
	}

	public void Update(int k, T a)
	{
		k += N - 1;
		dat[k] = a;
		while(k > 0)
		{
			k = (k - 1) / 2;
			dat[k] = Func(dat[k * 2 + 1], dat[k * 2 + 2]);
		}
	}

	public T Query(int a, int b, int k = 0, int l = 0, int r = -1)
	{
		if(r == -1)
			r = N;

		if(r <= a || b <= l)
			return INI;

		if(a <= l && r <= b)
			return dat[k];
		else
		{
			T vl = Query(a, b, k * 2 + 1, l, (l + r) / 2);
			T vr = Query(a, b, k * 2 + 2, (l + r) / 2, r);
			return Func(vl, vr);
		}
	}
}

public static class BinaryRepresentation
{
	/*
	* initialize: array = { 0, 1, 2, ..., N - 1 } 
	* do { ... } while(nextPermutaion(ref array));
	*/
	private static bool nextPermutation(ref int[] array)
	{
		int len = array.Length;
		int i = len - 2;
		while((i >= 0) && (array[i] > array[i + 1]))
			i--;
		if(i < 0)
			return false;

		int pivot = array[i];
		int j = i + 1;
		while((j < len - 1) && (array[j + 1] > pivot))
			j++;
		
		int tmp = array[i];
		array[i] = array[j];
		array[j] = tmp;
		
		Array.Reverse(array, i + 1, len - i - 1);

		return true;
	}

	/* 
	* nCk
	* initialize: comb = (1 << k) - 1
	* while(comb < (1 << n)) { ...; comb = nextCombination(comb); };
	*/
	public static int nextCombination(int comb)
	{
		int x = comb & -comb;
		int y = comb + x;
		return (((comb & ~y) /x) >> 1) | y;
	}

	public static int popcnt(int v) {
		v = v - ((v >> 1) & 0x55555555);
		v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
		return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24;
	}

	public static long popcnt(long v) {
		v = v - ((v >> 1) & 0x5555555555555555);
		v = (v & 0x3333333333333333) + ((v >> 2) & 0x3333333333333333);
		return ((v + (v >> 4) & 0xF0F0F0F0F0F0F0F) * 0x101010101010101) >> 56;
	}
}

public static class MyIO
{
	private static string[] args = null;
	private static int num = -1;
	private static int used = -1;

	private static string getArg()
	{
		if(used == num)
		{
			args = Console.ReadLine().Split(' ');
			num = args.Length;
			used = 0;
		}
		return args[used++];
	}

	public static int GetInt() => int.Parse(getArg());
	public static long GetLong() => long.Parse(getArg());
	public static double GetDouble() => double.Parse(getArg());
	public static decimal GetDecimal() => decimal.Parse(getArg());
	public static string GetString() => getArg();
	public static char GetChar() => getArg()[0];
	public static int[] GetInts(long N) => Enumerable.Range(0, (int)N).Select(_ => GetInt()).ToArray();
	public static long[] GetLongs(long N) => Enumerable.Range(0, (int)N).Select(_ => GetLong()).ToArray();
	public static double[] GetDoubles(long N) => Enumerable.Range(0, (int)N).Select(_ => GetDouble()).ToArray();
	public static decimal[] GetDecimals(long N) => Enumerable.Range(0, (int)N).Select(_ => GetDecimal()).ToArray();
	public static string[] GetStrings(long N) => Enumerable.Range(0, (int)N).Select(_ => GetString()).ToArray();
}

public static class MyUtil
{
	public static void chmax<T>(ref T x, T y) where T : IComparable<T>
	{
		if(x.CompareTo(y) < 0)
			x = y;
	}

	public static void chmin<T>(ref T x, T y) where T : IComparable<T>
	{
		if(x.CompareTo(y) > 0)
			x = y;
	}

	public static void swap<T>(ref T x, ref T y)
	{
		T tmp = x;
		x = y;
		y = tmp;
	}
}

Measured memory_bytes: 23820