#!/usr/bin/env python3
import sys
import numpy as np

input = sys.stdin.readline
mod = 998244353


def I():
    return int(input())


def MI():
    return map(int, input().split())



N, K = MI()

steps = set()
for _ in range(K):
    l, r = MI()
    steps |= set(range(l, r + 1))

dp = np.zeros(N)
dp[0] = 1

for i in range(N):
    for s in steps:
        tmp = i - s
        if tmp >= 0:
            dp[i] += dp[tmp]
            dp[i] %= mod

print(int(dp[N - 1]))
