#include <iostream>
#include <vector>
#include <string>
#include <unordered_map>

using namespace std;

vector<string> get_subsequences(string word) {
    vector<string> subsequences;

    for (int i = 0; i < 1 << word.length(); i++) {
        string s;
        for (int j = 0; j < word.length(); j++) {
            if ((i >> j) & 1) { // binary mask for every combination
                s += word[j];
            }
        }
        subsequences.push_back(s);
    }

    return subsequences;
}

int main() {
    int n, q;
    string word;

    cin >> n >> q;
    cin >> word;
    int index;
    char letter;

    q++;
    while (q--) {
        int ans = 0;
        unordered_map<string, int> subsequence_count;
        vector<string> subsequences = get_subsequences(word);

        for (int i = 0; i < subsequences.size(); i++) {
            subsequence_count[subsequences[i]]++;
        }

        for (auto p : subsequence_count) {
            if (p.second >= 2) {
                ans++;
            }
        }
        cout << ans << endl;

        if (q > 0) {
            cin >> index >> letter;
            word[index - 1] = letter;
        }
    }

    return 0;
}