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#include "bits/stdc++.h"

#define int long long
#define pi pair<long long, long long>
#define a3 array<long long, 3>

#define meow main

using namespace std;

void solve(const string &s) {
  unordered_map<string, int> A;
  int res = 0;
  for(int i=0; i<(1<<s.size()); i++) {
    string to_add;
    int mask = i;
    int k=0;
    while(mask) {
      if(mask%2) to_add.push_back(s[k]);
      k++;
      mask/=2;
    }
    A[to_add]++;
    res += (A[to_add] == 2);
  }

  cout << res << '\n';
}

signed meow() {
  cin.tie((ostream *)!ios::sync_with_stdio(false));
  int n, q;
  cin >> n >> q;
  string s;
  cin >> s;
  solve(s);
  while (q--) {
    int i; cin >> i;
    char c; cin >> c;
    s[i-1] = c;
    solve(s);
  }
  return 0;
}