// doot diddly donger cuckerino Hahahahahah


#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace __gnu_cxx;
using namespace std;

using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using vi = vector<int>;

template <typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const ld PI = acos(-1);

template <typename T> inline T mini(T& x, T y) { return x = min(x, y); }
template <typename T> inline T maxi(T& x, T y) { return x = max(x, y); }
mt19937 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());







#ifdef LOCAL
void signalHandler(int) {
  throw "Abort detected";
}
#endif

void doReplace() {
}

template <typename T, typename U, typename...Vs>
void doReplace(T &t, const U &u, Vs &&...vs) {
  t = u;
  doReplace(vs...);
}

template <typename T, typename...Us>
T minim(T &was, const T &cand, Us &&...us) {
  if (was > cand) {
    was = cand;
    doReplace(us...);
  }
  return was;
}

template <typename T, typename...Us>
T maxim(T &was, const T &cand, Us &&...us) {
  if (was < cand) {
    was = cand;
    doReplace(us...);
  }
  return was;
}

template <typename T>
T gcd(T a, T b) {
  a = abs(a);
  b = abs(b);
  while (b != 0) {
    a = a % b;
    swap(a, b);
  }
  return a;
}

template <typename T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}

template <typename T>
T power(const T& a, long long b) {
  if (b == 0) {
    return 1;
  }
  if ((b & 1) == 0) {
    T res = power(a, b >> 1);
    return res * res;
  } else {
    return power(a, b - 1) * a;
  }
}

long long power(long long a, long long b, long long mod) {
  long long res = 1;
  while (b) {
    if (b & 1) {
      res = (res * a) % mod;
    }
    a = (a * a) % mod;
    b /= 2;
  }
  return res;
}

template <typename T>
T factorial(int n) {
  T result = 1;
  for (int i = 2; i <= n; i++) {
    result *= i;
  }
  return result;
}

template <typename T>
std::vector<T> factorials(int length) {
  std::vector<T> result(length);
  if (length > 0) {
    result[0] = 1;
  }
  for (int i = 1; i < length; i++) {
    result[i] = result[i - 1] * i;
  }
  return result;
}

template <typename T>
std::vector<T> powers(T base, int length) {
  std::vector<T> result(length);
  if (length > 0) {
    result[0] = 1;
  }
  for (int i = 1; i < length; i++) {
    result[i] = result[i - 1] * base;
  }
  return result;
}


template <typename T>
T inverse(T a, T m) {
  T u = 0, v = 1;
  while (a != 0) {
    T t = m / a;
    m -= t * a; swap(a, m);
    u -= t * v; swap(u, v);
  }
  assert(m == 1);
  return u;
}

template <typename T>
class Modular {
public:
  using Type = typename decay<decltype(T::value)>::type;
  
  constexpr Modular() : value() {}
  template <typename U>
  Modular(const U& x) {
    value = normalize(x);
  }
  
  template <typename U>
  static Type normalize(const U& x) {
    Type v;
    if (-mod() <= x && x < mod()) v = static_cast<Type>(x);
    else v = static_cast<Type>(x % mod());
    if (v < 0) v += mod();
    return v;
  }
  
  const Type& operator()() const { return value; }
  template <typename U>
  explicit operator U() const { return static_cast<U>(value); }
  constexpr static Type mod() { return T::value; }
  
  Modular& operator+=(const Modular& other) { if ((value += other.value) >= mod()) value -= mod(); return *this; }
  Modular& operator-=(const Modular& other) { if ((value -= other.value) < 0) value += mod(); return *this; }
  template <typename U> Modular& operator+=(const U& other) { return *this += Modular(other); }
  template <typename U> Modular& operator-=(const U& other) { return *this -= Modular(other); }
  Modular& operator++() { return *this += 1; }
  Modular& operator--() { return *this -= 1; }
  Modular operator++(int) { Modular result(*this); *this += 1; return result; }
  Modular operator--(int) { Modular result(*this); *this -= 1; return result; }
  Modular operator-() const { return Modular(-value); }
  
  template <typename U = T>
  typename enable_if<is_same<typename Modular<U>::Type, int>::value, Modular>::type& operator*=(const Modular& rhs) {
#ifdef _WIN32
    uint64_t x = static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value);
    uint32_t xh = static_cast<uint32_t>(x >> 32), xl = static_cast<uint32_t>(x), d, m;
    asm(
      "divl %4; \n\t"
      : "=a" (d), "=d" (m)
      : "d" (xh), "a" (xl), "r" (mod())
    );
    value = m;
#else
    value = normalize(static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value));
#endif
    return *this;
  }
  template <typename U = T>
  typename enable_if<is_same<typename Modular<U>::Type, int64_t>::value, Modular>::type& operator*=(const Modular& rhs) {
    int64_t q = static_cast<int64_t>(static_cast<long double>(value) * rhs.value / mod());
    value = normalize(value * rhs.value - q * mod());
    return *this;
  }
  template <typename U = T>
  typename enable_if<!is_integral<typename Modular<U>::Type>::value, Modular>::type& operator*=(const Modular& rhs) {
    value = normalize(value * rhs.value);
    return *this;
  }
  
  Modular& operator/=(const Modular& other) { return *this *= Modular(inverse(other.value, mod())); }
  
  template <typename U>
  friend bool operator==(const Modular<U>& lhs, const Modular<U>& rhs);
  
  template <typename U>
  friend bool operator<(const Modular<U>& lhs, const Modular<U>& rhs);
  
  template <typename U>
  friend std::istream& operator>>(std::istream& stream, Modular<U>& number);

private:
  Type value;
};

template <typename T> bool operator==(const Modular<T>& lhs, const Modular<T>& rhs) { return lhs.value == rhs.value; }
template <typename T, typename U> bool operator==(const Modular<T>& lhs, U rhs) { return lhs == Modular<T>(rhs); }
template <typename T, typename U> bool operator==(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) == rhs; }

template <typename T> bool operator!=(const Modular<T>& lhs, const Modular<T>& rhs) { return !(lhs == rhs); }
template <typename T, typename U> bool operator!=(const Modular<T>& lhs, U rhs) { return !(lhs == rhs); }
template <typename T, typename U> bool operator!=(U lhs, const Modular<T>& rhs) { return !(lhs == rhs); }

template <typename T> bool operator<(const Modular<T>& lhs, const Modular<T>& rhs) { return lhs.value < rhs.value; }

template <typename T> Modular<T> operator+(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) += rhs; }
template <typename T, typename U> Modular<T> operator+(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) += rhs; }
template <typename T, typename U> Modular<T> operator+(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) += rhs; }

template <typename T> Modular<T> operator-(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) -= rhs; }
template <typename T, typename U> Modular<T> operator-(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) -= rhs; }
template <typename T, typename U> Modular<T> operator-(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) -= rhs; }

template <typename T> Modular<T> operator*(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) *= rhs; }
template <typename T, typename U> Modular<T> operator*(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) *= rhs; }
template <typename T, typename U> Modular<T> operator*(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) *= rhs; }

template <typename T> Modular<T> operator/(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) /= rhs; }
template <typename T, typename U> Modular<T> operator/(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) /= rhs; }
template <typename T, typename U> Modular<T> operator/(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) /= rhs; }

template<typename T, typename U>
Modular<T> power(const Modular<T>& a, const U& b) {
  assert(b >= 0);
  Modular<T> x = a, res = 1;
  U p = b;
  while (p > 0) {
    if (p & 1) res *= x;
    x *= x;
    p >>= 1;
  }
  return res;
}

template <typename T>
string to_string(const Modular<T>& number) {
  return to_string(number());
}

template <typename T>
std::ostream& operator<<(std::ostream& stream, const Modular<T>& number) {
  return stream << number();
}

template <typename T>
std::istream& operator>>(std::istream& stream, Modular<T>& number) {
  typename common_type<typename Modular<T>::Type, int64_t>::type x;
  stream >> x;
  number.value = Modular<T>::normalize(x);
  return stream;
}

/*
using ModType = int;

struct VarMod { static ModType value; };
ModType VarMod::value;
ModType& md = VarMod::value;
using Mint = Modular<VarMod>;
*/

constexpr int md = 998244353;
using Mint = Modular<std::integral_constant<decay<decltype(md)>::type, md>>;

class DLeapingTak {
public:
  
  void solve(std::istream& cin, std::ostream& cout) {
    int n, k;
    cin >> n >> k;
    vector<array<int, 2>> vec(k);
    for (int i = 0; i < k; ++i) {
      cin >> vec[i][0] >> vec[i][1];
    }
    vector<Mint> dp(n + 1);
    dp[0] = 0;
    dp[1] = 1;
    for (int i = 2; i <= n; ++i) {
      Mint now = 0;
      for (int j = 0; j < k; ++j) {
        int end = i - vec[j][1] - 1;
        int start = i - vec[j][0];
        maxi(end, 0);
        maxi(start, 0);
        now += dp[start];
        now -= dp[end];
      }
      dp[i] = dp[i - 1] + now;
    }
    cout << dp[n] - dp[n - 1] << endl;
  }
};

int32_t main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    std::cout.tie(nullptr);
	DLeapingTak solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}


Measured memory_bytes: 3924