#include <bits/stdc++.h>
using namespace std;
template <int MOD_>
struct modnum {
  static constexpr int MOD = MOD_;
  static_assert(MOD_ > 0, "MOD must be positive");

 private:
  using ll = long long;
  int v;
  static int minv(int a, int m) {
    a %= m;
    assert(a);
    return a == 1 ? 1 : int(m - ll(minv(m, a)) * ll(m) / a);
  }

 public:
  modnum() : v(0) {}
  modnum(ll v_) : v(int(v_ % MOD)) {
    if (v < 0) v += MOD;
  }
  explicit operator int() const { return v; }
  friend std::ostream& operator<<(std::ostream& out, const modnum& n) {
    return out << int(n);
  }
  friend std::istream& operator>>(std::istream& in, modnum& n) {
    ll v_;
    in >> v_;
    n = modnum(v_);
    return in;
  }
  friend bool operator==(const modnum& a, const modnum& b) {
    return a.v == b.v;
  }
  friend bool operator!=(const modnum& a, const modnum& b) {
    return a.v != b.v;
  }
  modnum inv() const {
    modnum res;
    res.v = minv(v, MOD);
    return res;
  }
  friend modnum inv(const modnum& m) { return m.inv(); }
  modnum neg() const {
    modnum res;
    res.v = v ? MOD - v : 0;
    return res;
  }
  friend modnum neg(const modnum& m) { return m.neg(); }
  modnum operator-() const { return neg(); }
  modnum operator+() const { return modnum(*this); }
  modnum& operator++() {
    v++;
    if (v == MOD) v = 0;
    return *this;
  }
  modnum& operator--() {
    if (v == 0) v = MOD;
    v--;
    return *this;
  }
  modnum& operator+=(const modnum& o) {
    v += o.v;
    if (v >= MOD) v -= MOD;
    return *this;
  }
  modnum& operator-=(const modnum& o) {
    v -= o.v;
    if (v < 0) v += MOD;
    return *this;
  }
  modnum& operator*=(const modnum& o) {
    v = int(ll(v) * ll(o.v) % MOD);
    return *this;
  }
  modnum& operator/=(const modnum& o) { return *this *= o.inv(); }
  friend modnum operator++(modnum& a, int) {
    modnum r = a;
    ++a;
    return r;
  }
  friend modnum operator--(modnum& a, int) {
    modnum r = a;
    --a;
    return r;
  }
  friend modnum operator+(const modnum& a, const modnum& b) {
    return modnum(a) += b;
  }
  friend modnum operator-(const modnum& a, const modnum& b) {
    return modnum(a) -= b;
  }
  friend modnum operator*(const modnum& a, const modnum& b) {
    return modnum(a) *= b;
  }
  friend modnum operator/(const modnum& a, const modnum& b) {
    return modnum(a) /= b;
  }
};
template <typename T>
T pow(T a, long long b) {
  assert(b >= 0);
  T r = 1;
  while (b) {
    if (b & 1) r *= a;
    b >>= 1;
    a *= a;
  }
  return r;
}
using num = modnum<998244353>;
int main() {
  ios_base::sync_with_stdio(false), cin.tie(nullptr);
  using ll = long long;
  int n, m;
  cin >> n >> m;
  vector<vector<vector<int> > > edges(2, vector<vector<int> >(n));
  for (int i = 0; i < m; i++) {
    int u, v;
    cin >> u >> v;
    u--;
    v--;
    edges[0][u].push_back(v);
    edges[1][v].push_back(u);
  }
  const ll MAXR = 1e16;
  {
    ll ans = MAXR;
    int R = 20;
    vector<ll> dist(n, MAXR);
    dist[0] = 0;
    for (int r = 0; r < R; r++) {
      vector<bool> vis(n, false);
      priority_queue<pair<ll, int> > cur;
      for (int i = 0; i < n; i++) cur.push({-dist[i], i});
      while (!cur.empty()) {
        pair<ll, int> z = cur.top();
        cur.pop();
        int v = z.second;
        if (vis[v]) continue;
        vis[v] = true;
        for (int w : edges[r & 1][v]) {
          if (dist[w] > dist[v] + 1) {
            dist[w] = dist[v] + 1;
            cur.push({-dist[w], w});
          }
        }
      }
      ans = min(ans, dist[n - 1] + (1ll << r) - 1);
    }
    if (ans < MAXR) {
      cout << ans << '\n';
      return 0;
    }
  }
  {
    vector<vector<int> > e2(2 * n);
    for (int v = 0; v < n; v++) {
      for (int w : edges[0][v]) {
        e2[v].push_back(w);
        e2[w + n].push_back(v + n);
      }
    }
    ll SW = 1e8;
    vector<ll> dist(2 * n, MAXR);
    dist[0] = 0;
    vector<bool> vis(2 * n, false);
    priority_queue<pair<ll, int> > cur;
    for (int i = 0; i < 2 * n; i++) cur.push({-dist[i], i});
    while (!cur.empty()) {
      pair<ll, int> z = cur.top();
      cur.pop();
      int v = z.second;
      if (vis[v]) continue;
      vis[v] = true;
      for (int w : e2[v]) {
        if (dist[w] > dist[v] + 1) {
          dist[w] = dist[v] + 1;
          cur.push({-dist[w], w});
        }
      }
      {
        int w = (v + n) % (2 * n);
        if (dist[w] > dist[v] + SW) {
          dist[w] = dist[v] + SW;
          cur.push({-dist[w], w});
        }
      }
    }
    ll ans = min(dist[n - 1], dist[n + n - 1]);
    assert(ans < MAXR);
    ll nsw = ans / SW;
    ll ne = ans % SW;
    num z = pow(num(2), nsw) + ne - 1;
    cout << z << '\n';
  }
}
