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

#define rep(i, b, e) for (int i = (b); i <= (e); i++)
#define per(i, b, e) for (int i = (e); i >= (b); i--)
#define FOR(i, b, e) rep(i, b, (e)-1)
#define SZ(x) int(x.size())
#define all(x) x.begin(), x.end()
#define pb push_back
#define mp make_pair
#define st first
#define nd second
using ll = long long;
using vi = vector<int>;
using pii = pair<int, int>;

auto& operator<<(auto& o, pair<auto, auto> p) {
  return o << "(" << p.st << ", " << p.nd << ")";
}
auto operator<<(auto& o, auto x) -> decltype(end(x), o) {
  o << "{";
  int i = 0;
  for (auto e : x)
    o << ", " + 2 * !i++ << e;
  return o << "}";
}
#ifdef LOCAL
#define deb(x...)                       \
  cerr << "[" #x "]: ", [](auto... $) { \
    ((cerr << $ << "; "), ...) << endl; \
  }(x)
#else
#define deb(...)
#endif

const ll mod = 998244353;

struct Matrix {
  int m[7][7] = {};
  int sz;

  Matrix() = default;

  Matrix(int n) : sz(n) {}

  Matrix operator*(const Matrix& other) const {
    Matrix n(sz);
    // assert(SZ(other.m) == SZ(m));
    for (int i = 0; i < sz; i++) {
      for (int j = 0; j < sz; j++) {
        ll sum = 0;
        for (int k = 0; k < sz; k++) {
          sum += ((ll)m[i][k] * other.m[k][j]) % mod;
        }
        n.m[i][j] = sum % mod;
      }
    }

    return n;
  }

  bool operator==(const Matrix& other) const {
    for (int i = 0; i < sz; i++)
      for (int j = 0; j < sz; j++)
        if (m[i][j] != other.m[i][j])
          return false;
    return true;
  }

  void dump() {
#ifdef LOCAL
    for (int i = 0; i < sz; i++) {
      for (int j = 0; j < sz; j++) {
        cerr << m[i][j] << " ";
      }
      cerr << "\n";
    }
#endif
  }
};

const int N = 50003;

string s;
int n;

const int ALF_SIZE = 6;

const int M = (1 << 16);
Matrix tree_end[M * 2];
Matrix tree_all[M * 2];
set<int> where[200];

Matrix create_all(char k) {
  Matrix m(ALF_SIZE + 1);
  for (int i = 0; i < ALF_SIZE + 1; i++) {
    m.m[i][i] = 1;
    m.m[k - 'a'][i] = 1;
  }
  return m;
}

int previous_occurance(char k, int i) {
  if (where[k].size() == 0) {
    return -1;
  }
  auto it = where[k].lower_bound(i);
  if (it == where[k].begin()) {
    return -1;
  }
  --it;
  return *it;
}

int next_occurance(char k, int i) {
  if (where[k].size() == 0) {
    return n;
  }
  auto it = where[k].upper_bound(i);
  if (it == where[k].end())
    return n;
  return *it;
}

Matrix create_end(char k, int idx) {
  Matrix m(ALF_SIZE);
  for (int i = 0; i < ALF_SIZE; i++) {
    m.m[i][i] = 1;
  }

  int p = previous_occurance(k, idx);
  for (char c = 'a'; c <= 'f'; c++) {
    if (c != k && previous_occurance(c, idx) > p) {
      m.m[k - 'a'][c - 'a'] = 1;
    }
  }
  return m;
}

Matrix id(int k) {
  Matrix res(k);
  for (int i = 0; i < k; i++)
    res.m[i][i] = 1;
  return res;
}

void init() {
  for (int i = 0; i < n; i++) {
    where[s[i]].insert(i);
    tree_all[i + M] = create_all(s[i]);
    tree_end[i + M] = create_end(s[i], i);
    // cerr << "Macierze dla " << i << "\n";
    tree_all[i + M].dump();
    // cerr << "end:\n";
    tree_end[i + M].dump();
  }

  for (int i = n; i < M; i++) {
    tree_all[i + M] = id(ALF_SIZE + 1);
    tree_end[i + M] = id(ALF_SIZE);
  }

  for (int i = M - 1; i >= 1; i--) {
    tree_all[i] = tree_all[i * 2 + 1] * tree_all[i * 2];
    tree_end[i] = tree_end[i * 2 + 1] * tree_end[i * 2];
  }

  // cerr << "Wszystkie macierze:\n";
  // for (int i = 1; i < n + n; i++) {
  //   cerr << i << ":\n";
  //   tree_all[i].dump();
  // }
}

int get_ans() {
  ll ans = 0;
  for (int i = 0; i < ALF_SIZE + 1; i++) {
    ans += tree_all[1].m[i][ALF_SIZE];
  }
  for (int i = 0; i < ALF_SIZE; i++) {
    if (where[i + 'a'].size() > 0) {
      for (int j = 0; j < ALF_SIZE; j++) {
        ans = (ans - tree_end[1].m[i][j] + mod) % mod;
      }
    }
  }
  return (ans - 1) % mod;
}

bool set_(const Matrix& m, int idx, Matrix* tree) {
  // cerr << "Chcom zebym zmienil " << idx << "\n";
  idx += M;
  if (tree[idx] == m)
    return false;

  tree[idx] = m;
  return true;
}

void upd(const Matrix& m, int idx, Matrix* tree) {
  idx += M;
  if (tree[idx] == m)
    return;
  tree[idx] = m;
  while (idx > 1) {
    idx /= 2;
    tree[idx] = tree[idx * 2 + 1] * tree[idx * 2];
  }
}

void apply_changes(Matrix* tree, const vi& idx) {
  priority_queue<int> wher;
  // cerr << "Applying changes\n";

  for (auto i : idx) {
    // cerr << "Pushing " << i << "\n";
    wher.push((i + M) / 2);
  }

  while (!wher.empty()) {
    int i = wher.top();
    wher.pop();
    // cerr << "Mnoze " << i << "\n";
    tree[i] = tree[i * 2 + 1] * tree[i * 2];
    if (i > 1) {
      wher.push(i / 2);
    }
  }
}

void update(int idx, char k) {
  char prev_c = s[idx];
  if (prev_c == k)
    return;

  s[idx] = k;
  where[k].insert(idx);
  where[prev_c].erase(idx);

  vi changes;
  // 1. Najpierw zmien idx-ta macierz
  upd(create_all(k), idx, tree_all);
  if (set_(create_end(k, idx), idx, tree_end)) {
    changes.push_back(idx);
  }
  // Matrix m_all = create_all(k);
  // Matrix m_end = create_end(k, idx);

  for (int i = 0; i < 6; i++) {
    char c = i + 'a';
    int p = next_occurance(c, idx);
    if (p != n) {
      if (set_(create_end(c, p), p, tree_end)) {
        changes.push_back(p);
      }
    }
  }

  apply_changes(tree_end, changes);
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie();

  int q;
  cin >> n >> q;

  cin >> s;

  init();
  // tree_all[1].dump();
  // tree_end[1].dump();
  cout << get_ans() << "\n";

  for (int i = 0; i < q; i++) {
    int k;
    char c;
    cin >> k >> c;

    update(k - 1, c);
    // tree_all[1].dump();
    // tree_end[1].dump();

    cout << get_ans() << "\n";
  }
}