Problem:
Score : 500 points

Problem Statement

You are given a string S of length N consisting of lowercase English letters.

Process Q queries of the following two types:

Type 1: change the i_q-th character of S to c_q. (Do nothing if the i_q-th character is already c_q.)

Type 2: answer the number of different characters occurring in the substring of S between the l_q-th and r_q-th characters (inclusive).

Constraints

N, Q, i_q, l_q, and r_q are integers.

S is a string consisting of lowercase English letters.

c_q is a lowercase English letter.

1 \leq N \leq 500000

1 \leq Q \leq 20000

|S| = N

1 \leq i_q \leq N

1 \leq l_q \leq r_q \leq N

There is at least one query of type 2 in each testcase.

Input

Input is given from Standard Input in the following format:

N
S
Q
Query_1
\vdots
Query_Q

Here, Query_i in the 4-th through (Q+3)-th lines is one of the following:

1 i_q c_q

2 l_q r_q

Output

For each query of type 2, print a line containing the answer.

Sample Input 1

7
abcdbbd
6
2 3 6
1 5 z
2 1 1
1 4 a
1 7 d
2 1 7

Sample Output 1

3
1
5

In the first query, cdbb contains three kinds of letters: b , c , and d, so we print 3.

In the second query, S is modified to abcdzbd.

In the third query, a contains one kind of letter: a, so we print 1.

In the fourth query, S is modified to abcazbd.

In the fifth query, S does not change and is still abcazbd.

In the sixth query, abcazbd contains five kinds of letters: a, b, c, d, and z, so we print 5.

Solution in Fortran (gfortran v4.8.4) (judge verdict: Time Limit Exceeded)

program main
  implicit none
  integer :: N, Q
  character(len=500000) :: S
  character(:),allocatable :: tmp
  character(len=1) :: c,b
  integer :: a
  integer :: i,j, l,r
  integer :: out
  read(*,*) N
  read(*,*) S
  read(*,*) Q

  do i = 1, Q
     read(*,'(i1,1x,a,1x,a)') a,b,c
     
     if (a == 1) then
        backspace(5)
        !read(*,'(i1,1x,g0,1x,a)') a,j,c
        read(*,*) a,j,c
        S(j:j) = c
     else
        backspace(5)
!        read(*,'(i1,1x,g0,1x,g0)') a,l,r
        read(*,*) a,l,r
        !tmp = S(l:r)
        call count_char(S(l:r),out)
        write(*,'(i0)') out
        !deallocate(tmp)
     end if

  end do
contains
  subroutine count_char(S,out)
    character(*) :: S
    integer :: out
    integer :: N
    integer :: i, tmp
    integer :: c(97:122)
    N = len_trim(S)
    c(97:122) = 0
    do i = 1,N
       c (ichar(S(i:i))) =  1
    end do
    out = count(c /=0)
  end subroutine count_char
end program main