#include <bits/stdc++.h>
using namespace std::literals::string_literals;
using i64 = std::int_fast64_t;
using std::cout;
using std::endl;
using std::cin;

template<typename T>
std::vector<T> make_v(size_t a){return std::vector<T>(a);}

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return std::vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

template<typename Monoid>
class segment_tree {
	using value_type = Monoid;
	using size_type = size_t;

	using binary_function = std::function<value_type(value_type, value_type)>;
	using checker = std::function<bool(value_type)>;
	
	const size_type size_;
	size_type height_;

	const value_type id;
	const binary_function bi_func;
	std::vector<value_type> data;
	
	private:
	const size_type get_height(const size_type& size) const {
		size_type height = 1;
		while(1 << height <= size) height++;
		return height;
	}
	const size_type base_size() const {
		return 1 << height_;
	}
	void meld(const size_type& index) {
		data[index] = bi_func(data[index << 1 ^ 0], data[index << 1 ^ 1]);
	}
	
	public:
	segment_tree(const size_type& size, const binary_function& bi_func, const value_type& id)
		: size_(size),
		  bi_func(bi_func),
		  id(id) {
		height_ = get_height(size);
		data.assign(base_size() << 1, id);
	}
	value_type fold(size_type left, size_type right) {
		value_type l_value = id,
				   r_value = id;

		for(left += base_size(), right += base_size();
			left < right;
			left >>= 1, right >>= 1) {
			if(left & 1)  l_value = bi_func(l_value, data[left++]);
			if(right & 1) r_value = bi_func(data[--right], r_value); 
		}
		return bi_func(std::move(l_value), std::move(r_value));
	}
	void update(size_type index, const value_type& value) {
		index += base_size();
		data[index] = bi_func(data[index], value);

		while(index >>= 1) meld(index);
	}
	void change(size_type index, const value_type& value) {
		index += base_size();
		data[index] = value;

		while(index >>= 1) meld(index);
	}
	const size_type search(const size_type & left, const checker & check) {
		value_type val = id;
		size_type k = left + base_size();
		while(true) {
			if(check(bi_func(val, data[k]))) {
				val = bi_func(val, data[k]);
				if(k & 1) {
					if((k + 1) & k) k = (k + 1) >> 1;
					else return size();
				} else {
					k = k + 1;
				}
			} else {
				if(k < base_size()) {
					k = k << 1 ^ 0;
				} else {
					return k - base_size();
				}
			}
		}
	}
	
	value_type operator[](const size_type& index) const {
		return data[index + base_size()];
	}
	const size_type size() const {
		return size_;
	}
	const bool empty() const {
		return data.empty();
	}
};

int main() {
	int n; scanf("%d", &n);
	std::string s; cin >> s;
	
	auto f = [&](int a, int b) { return a | b; };
	segment_tree<int> seg(n, f, 0);
	for(int i = 0; i < n; i++) seg.change(i, (1 << (s[i] - 'a')));
	
	int q; scanf("%d", &q);
	while(q--) {
		int type; scanf("%d", &type);
		
		if(type == 1) {
			int x; scanf("%d", &x);
			char c; cin >> c;
			
			seg.change(x - 1, (1 << (c - 'a')));
		} else if(type == 2) {
			int l, r; scanf("%d%d", &l, &r);
			l--;
			
			printf("%d\n", __builtin_popcount(seg.fold(l, r)));
		}
	}
	return 0;
}


Measured memory_bytes: 4996