#![allow(unused_parens)]
#![allow(unused_imports)]
#![allow(non_upper_case_globals)]
#![allow(non_snake_case)]
#![allow(unused_mut)]
#![allow(unused_variables)]
#![allow(dead_code)]

use itertools::Itertools;
use proconio::input;
use proconio::marker::{Chars, Usize1};

#[allow(unused_macros)]
#[cfg(debug_assertions)]
macro_rules! mydbg {
    //($arg:expr) => (dbg!($arg))
    //($arg:expr) => (println!("{:?}",$arg));
      ($($a:expr),*) => {
          eprintln!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
      }
}
#[cfg(not(debug_assertions))]
macro_rules! mydbg {
    ($($arg:expr),*) => {};
}

macro_rules! echo {
    ($($a:expr),*) => {
          $(println!("{}",$a))*
      }
}

use std::cmp::*;
use std::collections::*;
use std::ops::{Add, Div, Mul, Sub};

#[allow(dead_code)]
static INF_I64: i64 = 92233720368547758;
#[allow(dead_code)]
static INF_I32: i32 = 21474836;
#[allow(dead_code)]
static INF_USIZE: usize = 18446744073709551;
#[allow(dead_code)]
static M_O_D: usize = 1000000007;
#[allow(dead_code)]
static PAI: f64 = 3.1415926535897932;

trait IteratorExt: Iterator {
    fn toVec(self) -> Vec<Self::Item>;
}

impl<T: Iterator> IteratorExt for T {
    fn toVec(self) -> Vec<Self::Item> {
        self.collect()
    }
}

trait CharExt {
    fn toNum(&self) -> usize;
    fn toAlphabetIndex(&self) -> usize;
    fn toNumIndex(&self) -> usize;
}
impl CharExt for char {
    fn toNum(&self) -> usize {
        return *self as usize;
    }
    fn toAlphabetIndex(&self) -> usize {
        return self.toNum() - 'a' as usize;
    }
    fn toNumIndex(&self) -> usize {
        return self.toNum() - '0' as usize;
    }
}

trait VectorExt {
    fn joinToString(&self, s: &str) -> String;
}
impl<T: ToString> VectorExt for Vec<T> {
    fn joinToString(&self, s: &str) -> String {
        return self
            .iter()
            .map(|x| x.to_string())
            .collect::<Vec<_>>()
            .join(s);
    }
}

trait StringExt {
    fn get_reverse(&self) -> String;
}
impl StringExt for String {
    fn get_reverse(&self) -> String {
        self.chars().rev().collect::<String>()
    }
}

trait UsizeExt {
    fn pow(&self, n: usize) -> usize;
}
impl UsizeExt for usize {
    fn pow(&self, n: usize) -> usize {
        return ((*self as u64).pow(n as u32)) as usize;
    }
}

#[derive(Debug, Copy, Clone)]
pub struct ModInt {
    x: i64,
    global_mod: i64,
}
impl ModInt {
    pub fn new(p: i64) -> Self {
        let gm = 998244353;
        let a = (p % gm + gm) % gm;
        return ModInt {
            x: a,
            global_mod: gm,
        };
    }
    pub fn inv(self) -> Self {
        return self.pow(self.global_mod - 2);
    }
    pub fn pow(self, t: i64) -> Self {
        if (t == 0) {
            return ModInt::new(1);
        };
        let mut a = self.pow(t >> 1);
        a = a * a;
        if (t & 1 != 0) {
            a = a * self
        };
        return a;
    }
}
impl Add for ModInt {
    type Output = ModInt;
    fn add(self, other: ModInt) -> ModInt {
        let ret = self.x + other.x;
        return ModInt::new(ret);
    }
}
impl Sub for ModInt {
    type Output = ModInt;
    fn sub(self, other: ModInt) -> ModInt {
        let ret = self.x - other.x;
        return ModInt::new(ret);
    }
}
impl Mul for ModInt {
    type Output = ModInt;
    fn mul(self, other: ModInt) -> ModInt {
        let ret = self.x * other.x;
        return ModInt::new(ret);
    }
}
impl Div for ModInt {
    type Output = ModInt;
    fn div(self, other: ModInt) -> ModInt {
        let ret = self.x * other.inv().x;
        return ModInt::new(ret);
    }
}
impl std::string::ToString for ModInt {
    fn to_string(&self) -> String {
        return self.x.to_string();
    }
}

fn main() {
    input! {
       N: usize,
       K:usize,
    }
    let mut m = vec![];
    for _ in 0..K {
        input! {
            l:usize,
            r:usize,
        }
        m.push((l, r));
    }

    let mut sum = vec![ModInt::new(0); N + 10];
    let mut dp = vec![ModInt::new(0); N + 10];
    let mut sum2 = vec![ModInt::new(0); N + 10];
    sum[0] = sum[0] + ModInt::new(1);
    sum[1] = sum[1] - ModInt::new(1);
    sum2[1] = sum2[0] + sum[0];
    for i in 0..N {
        // if sum2[i + 1].x == 0 {
        //     continue;
        // }
        for j in 0..K {
            let (l, r) = m[j];
            if i + l >= N {
                continue;
            }
            sum[i + l] = sum[i + l] + sum2[i + 1];
            sum[min(i + r + 1, N)] = sum[min(i + r + 1, N)] - sum2[i + 1];
        }
        sum2[i + 2] = (sum2[i + 1] + sum[i + 1]);
    }

    echo!(sum2[N].to_string());
}


Measured memory_bytes: 11292