package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func configure(scanner *bufio.Scanner) {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
}
func getNextString(scanner *bufio.Scanner) string {
	scanned := scanner.Scan()
	if !scanned {
		panic("scan failed")
	}
	return scanner.Text()
}
func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}
func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}
func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}
func main() {
	fp := os.Stdin
	wfp := os.Stdout
	extra := 0
	if os.Getenv("I") == "IronMan" {
		fp, _ = os.Open(os.Getenv("END_GAME"))
		extra = 100
	}
	scanner := bufio.NewScanner(fp)
	configure(scanner)
	writer := bufio.NewWriter(wfp)
	defer func() {
		r := recover()
		if r != nil {
			fmt.Fprintln(writer, r)
		}
		writer.Flush()
	}()
	solve(scanner, writer)
	for i := 0; i < extra; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
}
func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	n := getNextInt(scanner)
	s := getNextString(scanner)
	q := getNextInt(scanner)
	dec := newDecomposition(n)
	for i := 0; i < n; i++ {
		dec.update(i, s[i])
	}
	for i := 0; i < q; i++ {
		t := getNextInt(scanner)
		if t == 1 {
			index := getNextInt(scanner) - 1
			c := getNextString(scanner)
			dec.update(index, c[0])
			continue
		}
		l := getNextInt(scanner) - 1
		r := getNextInt(scanner)
		fmt.Fprintln(writer, onescount32(dec.charset(l, r)))
	}
}

var pop8tab = [256]uint8{
	0x00, 0x01, 0x01, 0x02, 0x01, 0x02, 0x02, 0x03, 0x01, 0x02, 0x02, 0x03, 0x02, 0x03, 0x03, 0x04,
	0x01, 0x02, 0x02, 0x03, 0x02, 0x03, 0x03, 0x04, 0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05,
	0x01, 0x02, 0x02, 0x03, 0x02, 0x03, 0x03, 0x04, 0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05,
	0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05, 0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06,
	0x01, 0x02, 0x02, 0x03, 0x02, 0x03, 0x03, 0x04, 0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05,
	0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05, 0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06,
	0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05, 0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06,
	0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06, 0x04, 0x05, 0x05, 0x06, 0x05, 0x06, 0x06, 0x07,
	0x01, 0x02, 0x02, 0x03, 0x02, 0x03, 0x03, 0x04, 0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05,
	0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05, 0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06,
	0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05, 0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06,
	0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06, 0x04, 0x05, 0x05, 0x06, 0x05, 0x06, 0x06, 0x07,
	0x02, 0x03, 0x03, 0x04, 0x03, 0x04, 0x04, 0x05, 0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06,
	0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06, 0x04, 0x05, 0x05, 0x06, 0x05, 0x06, 0x06, 0x07,
	0x03, 0x04, 0x04, 0x05, 0x04, 0x05, 0x05, 0x06, 0x04, 0x05, 0x05, 0x06, 0x05, 0x06, 0x06, 0x07,
	0x04, 0x05, 0x05, 0x06, 0x05, 0x06, 0x06, 0x07, 0x05, 0x06, 0x06, 0x07, 0x06, 0x07, 0x07, 0x08,
}

func onescount32(x uint32) int {
	return int(pop8tab[x>>24] + pop8tab[x>>16&0xff] + pop8tab[x>>8&0xff] + pop8tab[x&0xff])
}

type decomposition struct {
	chunk  int
	bucket [][]uint32
}

func newDecomposition(n int) decomposition {
	bucket := make([][]uint32, 1)
	bucket[0] = make([]uint32, n)
	chunk := 8
	for i := 0; n > 1; i++ {
		n = (n-1)/chunk + 1
		bucket = append(bucket, make([]uint32, n))
	}
	return decomposition{
		chunk:  chunk,
		bucket: bucket,
	}
}
func (dec *decomposition) upleft(l int) int {
	return (l + dec.chunk - 1) / dec.chunk
}
func (dec *decomposition) upright(r int) int {
	return r / dec.chunk
}

func (dec *decomposition) update(index int, value byte) {
	dec.bucket[0][index] = 1 << uint(value-'a')
	h := len(dec.bucket)
	for i := 0; i < h-1; i++ {
		p := index / dec.chunk
		r := (p + 1) * dec.chunk
		if r >= len(dec.bucket[i]) {
			r = len(dec.bucket[i])
		}
		dec.bucket[i+1][p] = 1 << uint(value-'a')
		for j := p * dec.chunk; j < r; j++ {
			dec.bucket[i+1][p] = dec.bucket[i+1][p] | dec.bucket[i][j]
		}
		index /= dec.chunk
	}
}
func (dec *decomposition) charset(l, r int) uint32 {
	return dec.charseth(l, r, 0)
}
func (dec *decomposition) charseth(l, r, h int) uint32 {
	var u uint32
	ll := dec.upleft(l)
	rr := dec.upright(r)
	for i := l; i < r && i < ll*dec.chunk; i++ {
		u = u | dec.bucket[h][i]
	}
	if ll < rr {
		u = u | dec.charseth(ll, rr, h+1)
	}
	for i := rr * dec.chunk; i < r && ll <= rr; i++ {
		u = u | dec.bucket[h][i]
	}

	return u
}


Measured memory_bytes: 4608