/*
これを入れて実行
g++ code.cpp
./a.out
 */
 
#include <iostream>
#include <cstdio>
#include <stdio.h>
#include <vector>
#include <string>
#include <cstring>
#include <queue>
#include <deque>
#include <stack>
#include <algorithm>
#include <utility>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <cmath>
#include <math.h>
#include <tuple>
#include <iomanip>
#include <bitset>
#include <functional>
#include <cassert>
#include <random>

#define all(x) (x).begin(),(x).end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
 
using namespace std;
typedef long long ll;
typedef long double ld;
 
int dy4[4] = {-1, 0, +1, 0};
int dx4[4] = {0, +1, 0, -1};
int dy8[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
int dx8[8] = {0, 1, 1, 1, 0, -1, -1, -1};
 
const long long INF = 1LL << 60;
const ll MOD = 1e9 + 7;
 
bool greaterSecond(const pair<int, int>& f, const pair<int, int>& s){
    return f.second > s.second;
}
 
ll gcd(ll a, ll b){
	if (b == 0)return a;
	return gcd(b, a % b);
}
 
ll lcm(ll a, ll b){
    return a / gcd(a, b) * b;
}

ll conbinationMemo[100][100];

void cmemoInit(){
    rep(i, 100){
        rep(j, 100){
            conbinationMemo[i][j] = -1;
        }
    }
}
 
ll nCr(ll n, ll r){
    if(conbinationMemo[n][r] != -1) return conbinationMemo[n][r];
    if(r == 0 || r == n){
        return 1;
    } else if(r == 1){
        return n;
    }
    return conbinationMemo[n][r] = (nCr(n - 1, r) + nCr(n - 1, r - 1));
}
 
ll nPr(ll n, ll r){
    r = n - r;
    ll ret = 1;
    for (ll i = n; i >= r + 1; i--) ret *= i;
    return ret;
}
//-----------------------ここから-----------
struct LazySegmentTree{
    ll segTreeSize = 1;
    vector<ll> node;
    vector<ll> lazy;
    vector<bool> lazyf;

    void initRSQ(vector<ll> vec){
        while(segTreeSize < (ll)vec.size()){
            segTreeSize *= 2;
        }
        node.resize(2 * segTreeSize - 1, 0);
        lazy.resize(2 * segTreeSize - 1, 0);
        for(ll i = 0; i < (ll)vec.size(); i++){
            node[i + segTreeSize - 1] = vec[i];
        }
        for(ll i = segTreeSize - 2; i >= 0; i--){
            node[i] = node[2 * i + 1] + node[2 * i + 2];
        }
    }


    void evalRSQ(ll idx, ll l, ll r){
        if(lazy[idx] != 0){
            node[idx] += lazy[idx];
            if(r - l > 1){
                lazy[2*idx+1] += lazy[idx] / 2;
                lazy[2*idx+2] += lazy[idx] / 2;
            }
            lazy[idx] = 0;
        }
    }


    void updateRSQ(ll l, ll r, ll val, ll idx = 0, ll nowl = 0, ll nowr = -1){
        if(nowr < 0) nowr = segTreeSize;

        evalRSQ(idx, nowl, nowr);

        if(r <= nowl || nowr <= l) return;

        if(l <= nowl && nowr <= r){
            lazy[idx] = (nowr - nowl) * val;
            evalRSQ(idx, nowl, nowr);
        } else {
            updateRSQ(l, r, val, 2*idx+1, nowl, (nowl+nowr)/2);
            updateRSQ(l, r, val, 2*idx+2, (nowl + nowr) / 2, nowr);
            node[idx] = node[2*idx+1] + node[2*idx+2];
        }
    }
    void addRSQ(ll l, ll r, ll val, ll idx = 0, ll nowl = 0, ll nowr = -1){
        if(nowr < 0) nowr = segTreeSize;

        evalRSQ(idx, nowl, nowr);

        if(r <= nowl || nowr <= l) return;

        if(l <= nowl && nowr <= r){
            lazy[idx] += (nowr - nowl) * val;
            evalRSQ(idx, nowl, nowr);
        } else {
            addRSQ(l, r, val, 2*idx+1, nowl, (nowl+nowr)/2);
            addRSQ(l, r, val, 2*idx+2, (nowl + nowr) / 2, nowr);
            node[idx] = node[2*idx+1] + node[2*idx+2];
        }
    }


    ll getRSQ(ll l, ll r, ll idx = 0, ll nowl = 0, ll nowr = -1){
        if(nowr < 0) nowr = segTreeSize;
        if(r <= nowl || nowr <= l) return 0;

        evalRSQ(idx, nowl, nowr);
        if(l <= nowl && nowr <= r){
            return node[idx];
        }

        return getRSQ(l, r, 2*idx+1, nowl, (nowl + nowr)/2) + getRSQ(l, r, 2*idx+2, (nowl + nowr)/2, nowr);
    }
};
ll mod = 998244353;
int main(void){
    ll n, k;
    cin >> n >> k;
    vector<pair<ll,ll>> vec;
    rep(i, k){
        ll l, r;
        cin >> l >> r;
        vec.push_back({l, r});
    }
    sort(all(vec));

    LazySegmentTree s;
    vector<ll> tmp(n, 0);
    tmp[0] = 1;
    s.initRSQ(tmp);
    rep(i, n){
        ll now = s.getRSQ(i, i + 1);
        now %= mod;
        //cout << "now" << now << endl;
        rep(j, k){
            if(i + vec[j].first >= n) break;
            //cout << j << endl;
            s.updateRSQ(i + vec[j].first, min(n, i + vec[j].second + 1), now);
        }
    }
    cout << s.getRSQ(n - 1, n) % mod << endl;
}



Measured memory_bytes: 14568