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)

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
#include<tuple>
#include<unordered_set>
#include<unordered_map>
#include<random>
#include<array>
#include<cassert>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())



class BIT {//binary indexed tree, Fenwick treeとも
	int lg;
	std::vector<int> bit;
public:
	BIT() {
	}
	void init(int size) {
		bit.assign(size + 1, 0);
		lg = size;
		while (lg & lg - 1)lg &= lg - 1;
	}
	void add(int i, int x) {//i番目にx加える
		i++;//BIT添え字は1～ｎだから
		while (i < (int)bit.size()) {
			bit[i] += x;
			i += i & -i;
		}
	}
	int sum(int a)const {//[0,a]の和
		a++;
		int res = 0;
		while (0 < a) {
			res += bit[a];
			a -= a & -a;
		}
		return res;
	}
	int sum(int a, int b)const {//[a,b]の合計
		return sum(b) - sum(a - 1);
	}
};



int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	BIT bit[26];
	int n;
	string s;
	cin >> n >> s;

	rep(i, 26)bit[i].init(n);
	rep(i, s.size()) {
		int d = s[i] - 'a';
		bit[d].add(i, 1);
	}

	int q;
	cin >> q;
	rep(_, q) {
		int t;
		cin >> t;
		if (t == 1) {
			int p;
			char c;
			cin >> p >> c;
			p--;
			bit[s[p] - 'a'].add(p, -1);
			bit[c - 'a'].add(p, 1);
			s[p] = c;
		}
		else {
			int x, y;
			cin >> x >> y;
			x--; y--;
			int ans = 0;
			rep(i, 26) {
				int cnt = bit[i].sum(y);
				if (0 < x)cnt -= bit[i].sum(x - 1);
				if (cnt)ans++;
			}
			cout << ans << endl;
		}
	}


	return 0;
}