#include <bits/stdc++.h>
using namespace std;
const long long MOD = 998244353;
int main(){
  int N, Q;
  cin >> N >> Q;
  vector<int> L(Q), R(Q);
  for (int i = 0; i < Q; i++){
    cin >> L[i] >> R[i];
    L[i]--;
  }
  vector<int> X;
  X.push_back(0);
  X.push_back(N);
  for (int i = 0; i < Q; i++){
    X.push_back(L[i]);
    X.push_back(R[i]);
  }
  sort(X.begin(), X.end());
  X.erase(unique(X.begin(), X.end()), X.end());
  int M = X.size();
  for (int i = 0; i < Q; i++){
    L[i] = lower_bound(X.begin(), X.end(), L[i]) - X.begin();
    R[i] = lower_bound(X.begin(), X.end(), R[i]) - X.begin();
  }
  vector<int> imos(M + 1, 0);
  for (int i = 0; i < Q; i++){
    imos[L[i]]++;
    imos[R[i]]--;
  }
  for (int i = 0; i < M; i++){
    imos[i + 1] += imos[i];
  }
  bool ok = true;
  for (int i = 0; i < M - 1; i++){
    if (imos[i] > 0 && (X[i + 1] - X[i]) % 2 == 1){
      ok = false;
    }
  }
  if (!ok){
    cout << 0 << endl;
  } else {
    vector<int> A;
    int N2 = 0;
    for (int i = 0; i < M - 1; i++){
      if (imos[i] > 0){
        A.push_back(X[i + 1] - X[i]);
      } else {
        N2 += X[i + 1] - X[i];
      }
    }
    vector<long long> inv(N + 1);
    inv[1] = 1;
    for (int i = 2; i <= N; i++){
      inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    }
    vector<long long> fact(N + 1), finv(N + 1);
    fact[0] = 1;
    finv[0] = 1;
    for (int i = 1; i <= N; i++){
      fact[i] = fact[i - 1] * i % MOD;
      finv[i] = finv[i - 1] * inv[i] % MOD;
    }
    long long ans = 1;
    for (int a : A){
      a /= 2;
      ans *= fact[a * 2] % MOD * finv[a] % MOD * finv[a + 1] % MOD;
      ans %= MOD;
    }
    if (N2 >= 2){
      if (N2 % 2 == 0){
        long long x = fact[N2] * finv[N2 / 2] % MOD * finv[N2 / 2] % MOD;
        long long y = fact[N2] * finv[N2 / 2 + 1] % MOD * finv[N2 / 2 - 1] % MOD;
        ans *= x + MOD - y;
        ans %= MOD;
      } else {
        long long x = fact[N2] * finv[(N2 + 1) / 2] % MOD * finv[(N2 - 1) / 2] % MOD;
        long long y = fact[N2] * finv[(N2 + 1) / 2 + 1] % MOD * finv[(N2 - 1) / 2 - 1] % MOD;
        ans *= x + MOD - y;
        ans %= MOD;
      }
    }
    ans *= fact[N / 2];
    ans %= MOD;
    ans *= fact[(N + 1) / 2];
    ans %= MOD;
    cout << ans << endl;
  }
}