import java.util.*;
import java.io.*;
import java.math.*;
 
public class Main
{
    static class Pair{
        int l, r;
        public Pair(int l, int r){
            this.l = l;
            this.r = r;
        }
    }

    public static void process(int test_number)throws IOException
    {
        int n = ni(), k = ni(), l, r;
        Pair arr[] = new Pair[k];

        for(int i = 1; i <= k; i++){
            l = ni(); r = ni();
            arr[i - 1] = new Pair(l, r);
        }

        long dp[] = new long[n + 1], pref[] = new long[n + 1];
        dp[1] = 1l; pref[1] = 1l;

        for(int i = 2; i <= n; i++){
            
            for(int j = 0; j < k; j++){
                r = i - arr[j].l;
                l = i - arr[j].r;

                if(r >= 1){
                    l = Math.max(1, l);
                    dp[i] = (dp[i] + (pref[r] - pref[l - 1] + mod)% mod)% mod;
                }
            } 

            pref[i] = (pref[i - 1] + dp[i]) % mod; 
        }

        pn(dp[n]);
    }
 
    static final long mod = 998244353l;
    
    static FastReader sc;
    static PrintWriter out;
    public static void main(String[]args)throws IOException
    {
        out = new PrintWriter(System.out);
        sc = new FastReader();
 
        long s = System.currentTimeMillis();
        int t = 1;
        //t = ni();
        for(int i = 1; i <= t; i++)
            process(i);
 
        out.flush();
        System.err.println(System.currentTimeMillis()-s+"ms");
    }

    static void trace(Object... o){ System.err.println(Arrays.deepToString(o)); };
    static void pn(Object o){ out.println(o); }
    static void p(Object o){ out.print(o); }
    static int ni()throws IOException{ return Integer.parseInt(sc.next()); }
    static long nl()throws IOException{ return Long.parseLong(sc.next()); }
    static double nd()throws IOException{ return Double.parseDouble(sc.next()); }
    static String nln()throws IOException{ return sc.nextLine(); }
    static long gcd(long a, long b)throws IOException{ return (b==0)?a:gcd(b,a%b);}
    static int gcd(int a, int b)throws IOException{ return (b==0)?a:gcd(b,a%b); }
    static int bit(long n)throws IOException{ return (n==0)?0:(1+bit(n&(n-1))); }
    
    static class FastReader{ 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader(){ 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } 
  
        String next(){ 
            while (st == null || !st.hasMoreElements()){ 
                try{ st = new StringTokenizer(br.readLine()); } catch (IOException  e){ e.printStackTrace(); } 
            } 
            return st.nextToken(); 
        } 
  
        String nextLine(){ 
            String str = ""; 
            try{ str = br.readLine(); } catch (IOException e) { e.printStackTrace(); } 
            return str; 
        } 
    } 
}
