

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Random;
import java.util.StringTokenizer;

public final class Main {

    private static final int MOD = 998244353;

    public static void main(String[] args) {
        final FastScanner fs = new FastScanner();
        final int n = fs.nextInt();
        final int k = fs.nextInt();
        final int[][] segments = new int[k][2];
        for (int i = 0; i < k; i++) {
            segments[i] = new int[] { fs.nextInt(), fs.nextInt() };
        }
        final int[] dp = new int[n + 1];
        final int[] pref = new int[n + 1];
        dp[1] = pref[1] = 1;
        for (int i = 2; i <= n; i++) {
            for (int[] segment : segments) {
                if (i < segment[0]) {
                    continue;
                }
                final int left = segment[0];
                final int right = Math.max(i - segment[1] - 1, 0);
                final int val = (pref[i - left] - pref[right] + MOD) % MOD;
                dp[i] = (dp[i] + val) % MOD;
            }
            pref[i] = (pref[i - 1] + dp[i]) % MOD;
        }
//        System.out.println(Arrays.toString(dp));
//        System.out.println(Arrays.toString(pref));
        System.out.println(dp[n]);
    }

    static final class Utils {
        public static void shuffleSort(int[] arr) {
            shuffle(arr);
            Arrays.sort(arr);
        }

        public static void shuffleSort(long[] arr) {
            shuffle(arr);
            Arrays.sort(arr);
        }

        public static void shuffle(int[] arr) {
            final Random r = new Random();

            for (int i = 0; i <= arr.length - 2; i++) {
                final int j = i + r.nextInt(arr.length - i);
                swap(arr, i, j);
            }
        }

        public static void shuffle(long[] arr) {
            final Random r = new Random();

            for (int i = 0; i <= arr.length - 2; i++) {
                final int j = i + r.nextInt(arr.length - i);
                swap(arr, i, j);
            }
        }

        public static void swap(int[] arr, int i, int j) {
            final int t = arr[i];
            arr[i] = arr[j];
            arr[j] = t;
        }

        public static void swap(long[] arr, int i, int j) {
            final long t = arr[i];
            arr[i] = arr[j];
            arr[j] = t;
        }

        private Utils() {}
    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        private String next() {
            while (!st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    //noinspection CallToPrintStackTrace
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        int[] nextIntArray(int n) {
            final int[] a = new int[n];
            for (int i = 0; i < n; i++) { a[i] = nextInt(); }
            return a;
        }

        long[] nextLongArray(int n) {
            final long[] a = new long[n];
            for (int i = 0; i < n; i++) { a[i] = nextLong(); }
            return a;
        }
    }
}
