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: Runtime Error)

//by Top1
#include <bits/stdc++.h>
          
#define f first
#define s second
#define int long long
#define ld long double
#define ull unsigned long long
#define pii pair <int, int>
#define pll pair <long, long>
#define mp make_pair
#define pb push_back
#define pf push_front
#define pp pop_back
#define cerr cout
#define rev reverse
#define all(s) s.begin(), s.end()
#define sz(s) (int)s.size()
#define forn(i, a, b) for (int i = a; i <= b; i++)
#define boost ios_base::sync_with_stdio(false); cin.tie(0),cout.tie(0);
#define nxtp next_permutation
#define pvtp prev_permutation
#define KZ return 
#define x1 x21212121
#define y1 y21212121
#define sqr(x) x * x 
      
const int inf = (1e9) + 1;
const int mod = 479001599;
const int maxn = 1e5 + 111;
        
using namespace std;          

int n, t[4 * maxn];
string s;

void build(int v, int tl, int tr){
	if (tl == tr){
		int x = s[tl - 1] - 'a';
		x = (1 << x);
		t[v] = x;
		return;
	}                     
	int tm = (tl + tr) >> 1;
	build(v * 2, tl, tm);
	build(v * 2 + 1, tm + 1, tr);
	t[v] = t[v * 2] | t[v * 2 + 1];
}

void update(int v, int tl, int tr, int pos, int val){
	if (tl == tr){
		int x = (1 << val);
		t[v] = val;
		return;
	}
	int tm = (tl + tr) >> 1;
	if (pos <= tm)
		update(v * 2, tl, tm, pos, val);
	else
		update(v * 2 + 1, tm + 1, tr, pos, val);
	t[v] = t[v * 2] | t[v * 2 + 1];
}

int get(int v, int tl, int tr, int l, int r){
	if (tr < l || r < tl || l > r)
		return 0;
	if (tl >= l && tr <= r)
		return t[v];
	int tm = (tl + tr) >> 1;
	int x = get(v * 2, tl, tm, l, r);
	int y = get(v * 2 + 1, tm + 1, tr, l, r);
	return x | y;
}

void solve(){ 
	cin >> n >> s;

    build(1, 1, n);

    int q;

    cin >> q;

    while (q--){
    	int type;
    	cin >> type;
    	if (type == 1){
    		int pos;
    		char val;
    		cin >> pos >> val;
    		update(1, 1, n, pos, val - 'a');
    	}
    	else{
    		int l, r;
    		cin >> l >> r;
    		int x = get(1, 1, n, l, r);
    		cout << __builtin_popcount(x) << endl; 
    	}
    }
}                              
      
main(){
    boost;
    
    int q = 1;
 
    //cin >> q;
    
    while (q--){
        solve();
    }
}