#include<bits/stdc++.h>
using namespace std;
using ll=long long;
using P=pair<ll,ll>;
static const ll mod=998244353;
ll N,K;
ll dp[200005];
ll sum[200005];
int main(){
  cin>>N>>K;
 vector<P>A(K);
  for(ll i=0;i<K;i++){
  ll l,r;cin>>l>>r;
    P p(l,r);A[i]=p;
  }
  dp[0]=1;sum[0]=1;
  for(ll i=1;i<N;i++){
    for(ll j=0;j<K;j++){
    ll l=A[j].first;ll r=A[j].second;
      if(i-l<0){}else if(0<=i-l && 0<=i-r-1){
      dp[i]=(dp[i]+sum[i-l]-sum[i-r-1]+2*mod)%mod;
      }else
        dp[i]=(dp[i]+sum[i-l])%mod;
     }sum[i]=(sum[i-1]+dp[i])%mod;
  }cout<<dp[N-1]<<endl;
    
  return 0;
}  