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 C (GCC 5.4.1) (judge verdict: Time Limit Exceeded)

#include <stdio.h>

int main(){
  int i,j,n,q,c[500000],l,m,qq,a,b;
  char s[500000],cc;
  for(i=0;i<26;i++){
    c[i]=0;
  }
  scanf("%d",&n);
  scanf("%s",&s);
  for(i=0;i<n;i++){
    s[i]-='a';
    c[i]=1<<s[i];
  }
  scanf("%d",&q);
  for(i=0;i<q;i++){
  	scanf("%d",&qq);
    if(qq==1){
      scanf("%d %c",&a,&cc);
      c[a-1]=1<<(cc-'a');
    }else{
      scanf("%d %d",&a,&b);
      l=0;
      for(j=a-1;j<b;j++){
        l|=c[j];
      }
      m=0;
      for(j=0;j<26;j++){
        if(l&1==1) m++;
        l>>=1;
      }
      printf("%d\n",m);
    }
  }
  return(0);
}