import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools
from collections import deque

sys.setrecursionlimit(10**7)
inf = 10**20
mod = 998244353

DR = [1, -1, 0, 0]
DC = [0, 0, 1, -1]

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()

def main():
    N, K = LI()
    S = []
    for _ in range(K):
        l, r = LI()
        for i in range(l, r+1):
            S.append(i)
    dp = [0] * (N + 1)
    dp[0] = 1
    for i in range(N+1):
        for s in S:
            if i - s < 0:
                continue
            dp[i] += dp[i-s]
            dp[i] %= mod
    print(dp[N-1])

main()

