#include using namespace std; template struct ModInt{ long long val; constexpr ModInt(const long long &_val = 0) noexcept : val(_val) { normalize(); } void normalize(){ val = (val % Modulus + Modulus) % Modulus; } inline ModInt& operator+=(const ModInt& rhs) noexcept { if(val += rhs.val, val >= Modulus) val -= Modulus; return *this; } inline ModInt& operator-=(const ModInt& rhs) noexcept { if(val -= rhs.val, val < 0) val += Modulus; return *this; } inline ModInt& operator*=(const ModInt& rhs) noexcept { val = val * rhs.val % Modulus; return *this; } inline ModInt& operator/=(const ModInt& rhs) noexcept { val = val * inv(rhs.val).val % Modulus; return *this; } inline ModInt& operator++() noexcept { if(++val >= Modulus) val -= Modulus; return *this; } inline ModInt operator++(int) noexcept { ModInt t = val; if(++val >= Modulus) val -= Modulus; return t; } inline ModInt& operator--() noexcept { if(--val < 0) val += Modulus; return *this; } inline ModInt operator--(int) noexcept { ModInt t = val; if(--val < 0) val += Modulus; return t; } inline ModInt operator-() const noexcept { return (Modulus - val) % Modulus; } inline ModInt inv(void) const { return inv(val); } ModInt inv(const long long& n) const { long long a = n, b = Modulus, u = 1, v = 0; while(b){ long long t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } u %= Modulus; if(u < 0) u += Modulus; return u; } friend inline ModInt operator+(const ModInt& lhs, const ModInt& rhs) noexcept { return ModInt(lhs) += rhs; } friend inline ModInt operator-(const ModInt& lhs, const ModInt& rhs) noexcept { return ModInt(lhs) -= rhs; } friend inline ModInt operator*(const ModInt& lhs, const ModInt& rhs) noexcept { return ModInt(lhs) *= rhs; } friend inline ModInt operator/(const ModInt& lhs, const ModInt& rhs) noexcept { return ModInt(lhs) /= rhs; } friend inline bool operator==(const ModInt& lhs, const ModInt& rhs) noexcept { return lhs.val == rhs.val; } friend inline bool operator!=(const ModInt& lhs, const ModInt& rhs) noexcept { return lhs.val != rhs.val; } friend inline istream& operator>>(istream& is, ModInt& x) noexcept { is >> x.val; x.normalize(); return is; } friend inline ostream& operator<<(ostream& os, const ModInt& x) noexcept { return os << x.val; } }; struct Combination{ vector memo, memoinv, inv; const long long mod; Combination(const int &N, const long long &m) : memo(N + 1), memoinv(N + 1), inv(N + 1), mod(m){ memo[0] = memo[1] = 1; memoinv[0] = memoinv[1] = 1; inv[1] = 1; for(int i = 2; i <= N; ++i){ memo[i] = memo[i - 1] * i % mod; inv[i] = mod - inv[mod % i] * (m / i) % mod; memoinv[i] = memoinv[i - 1] * inv[i] % mod; } } inline long long fact(const long long &n) const { return memo[n]; } inline long long factinv(const long long &n) const { return memoinv[n]; } inline long long ncr(const long long &n, const long long &r) const { if(n < r || r < 0) return 0; return (memo[n] * memoinv[r] % mod) * memoinv[n - r] % mod; } inline long long npr(const long long &n, const long long &r) const { if(n < r || r < 0) return 0; return (memo[n] % mod) * memoinv[n - r] % mod; } inline long long nhr(const long long &n, const long long &r) const { if(n == 0 && r == 0) return 1; return ncr(n + r - 1, r); } }; template struct BinaryIndexedTree{ int N; vector BIT; BinaryIndexedTree(const int &N): N(N), BIT(N + 1, 0){ } T get(int i){ return sum(i + 1) - sum(i); } void add(int i, T x){ i++; while(i <= N){ BIT[i] += x; i += i & -i; } } T sum(int i) const { T ans = 0; while(i > 0){ ans += BIT[i]; i -= i & -i; } return ans; } T sum(int L, int R) const { return sum(R) - sum(L); } int lower_bound(T x) const { if(x <= 0){ return 0; }else{ int v = 0, r = 1; while(r < N) r = r << 1; for(int len = r; len > 0; len = len >> 1){ if(v + len < N && BIT[v + len] < x){ x -= BIT[v + len]; v += len; } } return v; } } int upper_bound(T x) const { if(x < 0){ return 0; }else{ int v = 0, r = 1; while(r <= N) r = r << 1; for(int len = r; len > 0; len = len >> 1){ if(v + len <= N && BIT[v + len] <= x){ x -= BIT[v + len]; v += len; } } return v; } } }; const long long MOD = 998244353; using mint = ModInt<998244353>; int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); int n, m; cin >> n >> m; vector c(n, -1), check(n, 1); for(int i = 0; i < m; i++){ int p, k; cin >> p >> k; p--, k--; c[k] = p; check[p] = 0; } vector sum_c(n + 1), sum_check(n + 1); for(int i = 0; i < n; i++) sum_c[i + 1] = sum_c[i] + (c[i] != -1); for(int i = 0; i < n; i++) sum_check[i + 1] = sum_check[i] + (check[i]); BinaryIndexedTree BIT(n); Combination comb(n, MOD); mint ans = 0; mint cntc = 0, cntnc = 0; for(int i = 0; i < n; i++) if(check[i]) cntnc += n - i - 1; for(int i = 0; i < n; i++){ if(c[i] == -1){ mint plus = comb.fact(n - m - 2); plus *= i - sum_c[i]; plus *= cntnc; ans += plus; ans += cntc * comb.fact(n - m - 1); }else{ mint plus = sum_check[n] - sum_check[c[i]]; plus *= comb.fact(n - m - 1); plus *= i - sum_c[i]; ans += plus; ans += BIT.sum(c[i] + 1, n) * comb.fact(n - m); cntc += sum_check[c[i]]; BIT.add(c[i], 1); } } cout << ans << endl; }