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++14 (GCC 5.4.1) (judge verdict: Accepted)

#pragma GCC optimize ("O3", "unroll-loops")
#pragma GCC target ("avx")
#include <stdio.h>

constexpr char* S_OUT[31] = {
    "0\n", "1\n", "2\n", "3\n", "4\n", "5\n", "6\n", "7\n", "8\n", "9\n", "10\n",
    "11\n", "12\n", "13\n", "14\n", "15\n", "16\n", "17\n", "18\n", "19\n", "20\n",
    "21\n", "22\n", "23\n", "24\n", "25\n", "26\n", "27\n", "28\n", "29\n", "30\n"
};

constexpr unsigned int InputSize = 1e6;
constexpr unsigned int OutputSize = 1e5;
char Input[InputSize];
char* pointer = Input;
char Output[OutputSize];
char* m_buffer = Output;

inline unsigned int getInt(void){
    unsigned int res = 0;
    do{ res = 10 * res + (*(pointer++) - '0'); } while(*pointer >= '0');
    return res;
}

inline void out(const unsigned int v){
    char* str = S_OUT[v];
    while(*str) *(m_buffer++) = *(str++);
}

unsigned int n;
unsigned int N;
constexpr unsigned int SIZE = (1U << 19) + 1;
unsigned int data[2 * SIZE];

inline void set(void){
    n = getInt(); N = 1U << (31 - __builtin_clz(n)); while(N < n) N <<= 1;
    ++pointer; // \n
    unsigned int i, j;
    for(i = 0, j = N; i < n; ++i, ++j) data[j] = 1U << (*(pointer++) - 'a');
    for(i = N - 1; i ; --i){
      j = i << 1; data[i] = data[j] | data[j | 1U];
    }
}

inline void query(void){
    pointer += 3;
    if(*(pointer - 2) == '1'){
        unsigned int index = getInt() - 1;
        unsigned char idx = *((++pointer)++) - 'a';
        data[index += N] = 1U << idx;
        for(unsigned int i = index; i >= 2; i >>= 1) data[i >> 1] = data[i] | data[i ^ 1];
    }
    else{
        unsigned int l = getInt() + N - 1; pointer++;
        unsigned int r = getInt() + N;
        unsigned int res = 0;
        while(l < r){
            if(l & 1) res |= data[l++]; l >>= 1;
            if(r & 1) res |= data[--r]; r >>= 1;
        }
        out(__builtin_popcount(res));
    }
}

int main(void){
    fread(Input, sizeof(char), InputSize, stdin);
    set(); ++pointer;
    unsigned int q = getInt();
    while(q--) query();
    fwrite(Output, sizeof(char), m_buffer - Output, stdout);
    return 0;
}