0 pts...

#include <bits/stdc++.h>
using namespace std;
inline void init() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
}
template<typename any>struct odt {
	struct odt_node {
		int l, r;
		mutable any data;
		odt_node(int _l, int _r = -1, any _data = 0):l(_l), r(_r), data(_data) {}
		bool operator < (const odt_node &t) const {
			return l < t.l;
		}
	};
	std::set<odt_node> s;
	auto insert(int l, int r = -1, any k = 0) {return s.emplace(l, r, k);}
	inline auto split(int pos) {
		auto it = s.lower_bound(pos);
		if(it != s.end() and it->l == pos)return it;
		--it;
		int l = it->l, r = it->r;
		any k = it->data;
		s.erase(it);
		insert(l, pos-1, k);
		return insert(pos, r, k).first;
	}
	inline auto assign(int l,int r,any k) {
		auto it_r = split(r + 1), it_l = split(l);
		s.erase(it_l, it_r);
		return insert(l, r, k).first;
	}
	inline auto Ruq(int l, int r, any k) {
		int cnt = 0;
		auto it_r = split(r + 1), it_l = split(l);
		for(; it_l != it_r; ++it_l) {
			if((it_l -> data) == k)
				cnt++;
		}
		return cnt;
	}
	inline void Rsort(int l, int r) {
		auto it_r = split(r + 1), it_l = split(l);
		vector<pair<any, int> > Ins;
		Ins.clear();
		for(; it_l != it_r; ++it_l)
			Ins.push_back({it_l -> data, it_l->l - it_r->r + 1});	
		sort(Ins.begin(), Ins.end());
	}
};
odt<char> ODT;
int n, m;
int main() {
	init();
	cin >> n >> m;
	for(int i = 1; i <= n; ++i)
		ODT.insert(i, i, toupper(getchar()));
	while(m--) {
		int op, l, r;
		cin >> op;
		switch(op) {
			case 1 : {
				char k;
				cin >> l >> r >> k;
				cout << ODT.Ruq(l, r, toupper(k)) << "\n";
				break;
			}
			case 2 : {
				char k;
				cin >> l >> r >> k;
				ODT.assign(l, r, toupper(k));
				break;
			}
			case 3 : {
				cin >> l >> r;
				ODT.Rsort(l, r);
				break;
			}
		}
	}
	return 0;
}