#include <bits/stdc++.h>
using namespace std;

int main() {
	int N, Q;
	cin >> N >> Q;
	string S;
	cin >> S;
	
	while(Q--) {
		int cmd;
		cin >> cmd;
		
		if(cmd == 1) {
			int i; char c;
			cin >> i >> c, --i;
			
			S[i] = c;
		}
		
		if(cmd == 2) {
			string T;
			cin >> T;
			int M = T.size();
			
			bool flag = false;
			for(int i = 0; i <= N - M; ++i) {
				if(S.substr(i, M) == T) {
					flag = true;
					break;
				}
			}
			
			cout << (flag ? "Yes" : "No") << "\n";
		}
	}
}