#include <bits/stdc++.h>
using namespace std;
#define REP(i,x,n) for(int i=x;i<(int)n;i++)
#define rep(i,n) REP(i,0,n)
#define sp(p) cout<<setprecision(16)<<fixed<<p<<endl;
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define SORT(a) sort(all(a))
#define RSORT(a) sort(rall(a))
#define UNIQ(a) unique(all(a))
#define UNIQNUM(a) UNIQ(a)-a.begin()
#define UNIQIT(a) a.erase(UNIQ(a), a.end());
#define VOUT(v,i) rep(i,v.size())cout<<v[i]<<(i==v.size()-1?"\n":" ");
#define vout(v) VOUT(v,z);
#define vdbg(v,i) cout<<#v<<": ";for(int i=0;i<(int)v.size();i++){cout<<v[i]<<" ";}cout<<"\n";
#define vmin(v) *min_element(all(v))
#define vmax(v) *max_element(all(v))
#define vsum(v) accumulate(all(v), 0LL)
#define MOUT(m,r,c) rep(i,r){rep(j,c){cout<<m[i][j]<<" ";}cout<<endl;}
#define mout(m) MOUT(m,m.size(),m[0].size())
#define debg(a) cout<<#a<<": "<<a<<endl;
#define out(a) debg(a);
#define show(a) for(cont &y:a){for(cont &x:y){cout<<x<<" ";}cout<<endl;}
#define digit(a) to_string(a).length();
// template<class T>inline int out(const T &t){ print(t); putchar('\n'); return 0; }
// template<class T>inline T gcd(T a,T b){if(b==0)return a; return(gcd(b,a%b));}
// template<class T>inline T lcm(T a,T b){return a/gcd(a,b)*b;}
bool is_palindrome(string s){return s == string(s.rbegin(),s.rend());}
#define popcount __builtin_popcount
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> P;
typedef vector<ll> V;
typedef vector<vector<ll>> VV;
// const long long MOD=1000000007;
const long long INF = 1e18;
#define EPS (1e-7)
#define PI (acos(-1))
template<class T>
inline bool chmax(T &a, T b) {
    if(a < b) { a = b; return true; }
    return false;
}
template<class T>
inline bool chmin(T &a, T b) {
    if(a > b) { a = b; return true; }
    return false;
}

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;
    // }
};
const long long MOD = 998244353;
using mint = Fp<MOD>;

mint modpow(const mint &a,ll n){
    if(n==0)return 1;
    mint t=modpow(a,n/2);
    t=t*t;
    if(n&1)t=t*a;
    return t;
}




int main(){
    long long N;
    scanf("%lld",&N);
    long long K;
    scanf("%lld",&K);
    std::vector<long long> L(K);
    std::vector<long long> R(K);
    set<long long> s;
    for(int i = 0 ; i < K ; i++){
        scanf("%lld",&L[i]);
        scanf("%lld",&R[i]);
        for (long long j = L[i]; j <= R[i]; j++) {
            s.insert(j);
        }
    }
    vector<mint> dp(N+100);
    dp[1]=1;
    vector<mint> acc(N+100);
    // acc[1]=1;
    for (long long i = 1; i <= N; i++) {
        for (long long j = 0; j < K; j++) {
            // if(i-L[j]>0)
            //     dp[i] += dp[i-L[j]];
            // if(i-R[j]>0)
            //     dp[i] += dp[i-R[j]];
            if(i-L[j]>0)
                dp[i] += acc[i-L[j]];
            if(i-R[j]>1)
                dp[i] -= acc[i-R[j]-1];
            // if(i-L[j]>0 && i-R[j]>1)
            //     dp[i] += acc[i-L[j]] - acc[i-R[j]-1];
        }
        // for (auto& e: s) {
        //     if(i-e>0){
        //         dp[i] += dp[i-e];
        //     }else{
        //         break;
        //     }
        // }
        acc[i] += acc[i-1] + dp[i];
    }
    // for (auto& e: s) { cout << e << endl; }
    // vout(dp);
    // vout(acc);
    cout << dp[N] << endl;

    return 0;
}


Measured memory_bytes: 15556