#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic pop
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using mint = modint998244353;

constexpr int FACT_SIZE = 1000000;
mint Fact[FACT_SIZE + 1];
mint iFact[FACT_SIZE + 1];
const auto fact_init = [] {
    Fact[0] = mint::raw(1);
    for(int i = 1; i <= FACT_SIZE; ++i) {
        Fact[i] = Fact[i-1] * i;
    }
    iFact[FACT_SIZE] = Fact[FACT_SIZE].inv();
    for(int i = FACT_SIZE; i; --i) {
        iFact[i-1] = iFact[i] * i;
    }
    return false;
}();

mint comb(int n, int k) {
    if (k == 0) return mint::raw(1);
    assert(n >= 0 && k >= 0);
    if (k > n) return mint::raw(0);
    return Fact[n] * iFact[n - k] * iFact[k];
}

mint icomb(int n, int k) {
    return iFact[n] * Fact[n - k] * Fact[k];
}

mint fact(int n) {return Fact[n];}
mint perm(int n, int k) {
    assert(0 <= n);
    return Fact[n] * iFact[n - k];
}

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, q;
  cin >> n >> q;
  scc_graph g(n + 1);
  rep(_, q) {
    int l, r;
    cin >> l >> r;
    l--;
    for(int i = l; i <= r; i++) {
      g.add_edge(i, l);
      g.add_edge(i, r);
    }
  }
  vector<char> done(n);
  mint ans = 1;
  for(auto& c: g.scc()) {
    sort(all(c));
    int l = -1;
    for(int r: c) {
      if (l == -1) {
        l = r;
        continue;
      }
      int cnt = 0;
      for(int i = l; i < r; i++) {
        cnt += !done[i];
        done[i] = true;
      }
      if (cnt % 2) {
        cout << 0 << '\n';
        return 0;
      }
      ans *= comb(cnt, cnt / 2) - comb(cnt, cnt / 2 - 1);
      l = r;
    }
  }
  int rest = n - accumulate(all(done), 0);
  if (rest) {
    int a = (rest + 1) / 2, b = rest - a;
    mint v = comb(a + b, a);
    if (b - 1 >= 0) v -= comb(a + b, b - 1);
    ans *= v;
  }
  ans *= fact(n / 2);
  ans *= fact((n + 1) / 2);
  cout << ans.val() << '\n';
}