#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;

using u128 = unsigned __int128;
using i128 = __int128;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int N, Q;
    std::cin >> N >> Q;

    std::string s;
    std::cin >> s;

    while (Q--) {
        int op;
        std::cin >> op;
        if (op == 1) {
            int x;
            char c;
            std::cin >> x >> c;
            x--;
            s[x] = c;
        } else {
            std::string t;
            std::cin >> t;
            int sz = t.size();
            bool ok = false;
            for (int i = 0; i < N - sz + 1; i++) {
                if (s.substr(i, sz) == t) {
                    ok = true;
                    break;
                }                
            }
            std::cout << (ok ? "Yes\n" : "No\n");
        }
    }

    return 0;
}