#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long LL;
typedef long double ld;
typedef vector<ll>VI;
typedef pair<int,int>P;
#define VV(T) vector<vector<T>>
#define sz(x) int(x.size())
#define PI 3.1415926535897932384626433832795
#define rep(i, n) for (ll i = 0; i < (ll)n; i++)
#define reprev(i,n) for (ll i=(ll)n-1;i>=0;i--)
#define ALL(a)  (a).begin(),(a).end()
#define rALL(a) (a).rbegin(),(a).rend()
#define c_max(a, b) (((ll)a)>((ll)b)?(a):(b))
#define c_min(a,b) (((ll)a)<((ll)b)?(a):(b))
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
#define vmax(v) *max_element(ALL(v))
#define vmin(v) *min_element(ALL(v))
#define $(x) {cout<<#x<<" = " <<(x)<<endl;}
#define fi first
#define se second
#define MAX 100100//5
#define MAX2 200100
#define MAX6 1001001//6
#define MAX7 10010010//7
#define SENTINEL 2000000000//9
#define INF 1<<30
#define INFTY 1LL<<60
#define MAX_INT INT_MAX
#define Endl '\n'
#define CLR(mat) memset(mat, 0, sizeof(mat))
inline ll GCD(ll a,ll b){return b?GCD(b,a%b):a;}//最大公約数
inline ll lcm(ll a,ll b){return a*b/GCD(a,b);}//最小公倍数
template<class T> bool contain(const std::string& s, const T& v) {
   return s.find(v) != std::string::npos;
}
const int MOD = 998244353;

inline ll mod_add(ll a,ll b){return (a+b)%MOD;}
inline ll mod_sub(ll a,ll b){return (a+MOD-b)%MOD;}
inline ll mod_mul(ll a,ll b){return ((a%MOD)*(b%MOD))%MOD;}
inline ll mod_pow(ll x,ll n,ll mod=(ll)MOD){ll res=1;while(n>0){
if(n&1)res=res*x%mod;
x=x*x%mod;n>>=1;}return res;}
inline ll mod_inv(ll x){return mod_pow(x,MOD-2);}
inline ll mod_div(ll a, ll b){return mod_mul(a,mod_inv(b));}
const int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
// vector型から重複を削除 list.erase(unique(ALL(list)),list.end());
// g++ -o a a.cpp -Wall -lm -std=c++17
//push_back -> emplace_back


template<int MOD> struct Fp {
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
        if (val < 0) val += MOD;
    }
    constexpr int getmod() { return MOD; }
    constexpr Fp operator - () const noexcept {
        return val ? MOD - val : 0;
    }
    constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept {
        val += r.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr Fp& operator -= (const Fp& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr Fp& operator *= (const Fp& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr Fp& operator /= (const Fp& r) noexcept {
        long long a = r.val, b = MOD, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % MOD;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator == (const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};

// 二項係数ライブラリ
template<class T> struct BiCoef {
    vector<T> fact_, inv_, finv_;
    constexpr BiCoef() {}
    constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
        init(n);
    }
    constexpr void init(int n) noexcept {
        fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
        int MOD = fact_[0].getmod();
        for(int i = 2; i < n; i++){
            fact_[i] = fact_[i-1] * i;
            inv_[i] = -inv_[MOD%i] * (MOD/i);
            finv_[i] = finv_[i-1] * inv_[i];
        }
    }
    constexpr T com(int n, int k) const noexcept {
        if (n < k || n < 0 || k < 0) return 0;
        return fact_[n] * finv_[k] * finv_[n-k];
    }
    constexpr T fact(int n) const noexcept {
        if (n < 0) return 0;
        return fact_[n];
    }
    constexpr T inv(int n) const noexcept {
        if (n < 0) return 0;
        return inv_[n];
    }
    constexpr T finv(int n) const noexcept {
        if (n < 0) return 0;
        return finv_[n];
    }
};
using mint=Fp<MOD>;


 
// 区間加算にも対応した BIT
template <class Abel> struct BIT {
    vector<Abel> dat[2];
    Abel UNITY_SUM = 0;                     // to be set
    
    /* [1, n] */
    BIT(int n) { init(n); }
    void init(int n) { for (int iter = 0; iter < 2; ++iter) dat[iter].assign(n + 1, UNITY_SUM); }
    
    /* a, b are 1-indexed, [a, b) */
    inline void sub_add(int p, int a, Abel x) {
        for (int i = a; i < (int)dat[p].size(); i += i & -i)
            dat[p][i] = dat[p][i] + x;
    }
    inline void add(int a, int b, Abel x) {
        sub_add(0, a, x * -(a - 1)); sub_add(1, a, x); sub_add(0, b, x * (b - 1)); sub_add(1, b, x * (-1));
    }
    
    /* a is 1-indexed, [a, b) */
    inline Abel sub_sum(int p, int a) {
        Abel res = UNITY_SUM;
        for (int i = a; i > 0; i -= i & -i) res = res + dat[p][i];
        return res;
    }
    inline Abel sum(int a, int b) {
        return sub_sum(0, b - 1) + sub_sum(1, b - 1) * (b - 1) - sub_sum(0, a - 1) - sub_sum(1, a - 1) * (a - 1);
    }
    
    /* debug */
    void print() {
        for (int i = 1; i < (int)dat[0].size(); ++i) cout << sum(i, i + 1) << ",";
        cout << endl;
    }
};

int main(){ 
    ll n,k;cin>>n>>k;
    BIT<mint>dp(4*n);
    vector<P>K;
    rep(i,k){
        ll l,r;cin>>l>>r;
        K.emplace_back(P(l,r));
    }
    dp.add(1,2,1);
    for(int i=2;i<2*n;i++){
        for(int j=0;j<k;j++){
            if(i-K[j].fi>0 && i-K[j].se>0){
        dp.add(i,i+1,dp.sum(i-K[j].se,i-K[j].fi+1));
            }
            else if(i-K[j].fi>0 && i-K[j].se<=0){
                dp.add(i,i+1,dp.sum(1,i-K[j].fi+1));
            }
        }
    }
    cout<<dp.sum(n,n+1)<<endl;
}


Measured memory_bytes: 15640