### BUGGY CODE ###

def getN():
    return int(input())
def getNM():
    return map(int, input().split())
def getList():
    return list(map(int, input().split()))
def getArray(intn):
    return [int(input()) for i in range(intn)]
def input():
    return sys.stdin.readline().rstrip()
def rand_N(ran1, ran2):
    return random.randint(ran1, ran2)
def rand_List(ran1, ran2, rantime):
    return [random.randint(ran1, ran2) for i in range(rantime)]
def rand_ints_nodup(ran1, ran2, rantime):
  ns = []
  while len(ns) < rantime:
    n = random.randint(ran1, ran2)
    if not n in ns:
      ns.append(n)
  return sorted(ns)

def rand_query(ran1, ran2, rantime):
  r_query = []
  while len(r_query) < rantime:
    n_q = rand_ints_nodup(ran1, ran2, 2)
    if not n_q in r_query:
      r_query.append(n_q)
  return sorted(r_query)

from sys import exit

import sys
sys.setrecursionlimit(1000000000)
mod = 998244353

#############
# Main Code #
#############

#####segfunc#####
def segfunc(x, y):
    return min(x, y)
#################

#####ide_ele#####
ide_ele = 2 ** 63 - 1
#################

class LazySegmentTree:
    """
    init(init_val, ide_ele): 配列init_valで初期化 O(N)
    add(l, r, x): 区間[l, r)にxを加算 O(logN)
    query(l, r): 区間[l, r)をsegfuncしたものを返す O(logN)
    """
    def __init__(self, init_val, segfunc, ide_ele):
        """
        init_val: 配列の初期値
        segfunc: 区間にしたい操作
        ide_ele: 単位元
        num: n以上の最小の2のべき乗
        data: 値配列(1-index)
        lazy: 遅延配列(1-index)
        """
        n = len(init_val)
        self.segfunc = segfunc
        self.ide_ele = ide_ele
        self.num = 1 << (n - 1).bit_length()
        self.data = [ide_ele] * 2 * self.num
        self.lazy = [0] * 2 * self.num
        # 配列の値を葉にセット
        for i in range(n):
            self.data[self.num + i] = init_val[i]
        # 構築していく
        for i in range(self.num - 1, 0, -1):
            self.data[i] = self.segfunc(self.data[2 * i], self.data[2 * i + 1])

    def gindex(self, l, r):
            """
            伝搬する対象の区間を求める
            lm: 伝搬する必要のある最大の左閉区間
            rm: 伝搬する必要のある最大の右開区間
            """
            l += self.num
            r += self.num
            lm = l >> (l & -l).bit_length()
            rm = r >> (r & -r).bit_length()

            while r > l:
                if l <= lm:
                    yield l
                if r <= rm:
                    yield r
                r >>= 1
                l >>= 1
            while l:
                yield l
                l >>= 1

    def propagates(self, *ids):
        """
        遅延伝搬処理
        ids: 伝搬する対象の区間
        """
        for i in reversed(ids):
            v = self.lazy[i]
            if not v:
                continue
            self.lazy[2 * i] += v
            self.lazy[2 * i + 1] += v
            self.data[2 * i] += v
            self.data[2 * i + 1] += v
            self.lazy[i] = 0

    def add(self, l, r, x):
        """
        区間[l, r)の値にxを加算
        l, r: index(0-index)
        x: additional value
        """
        *ids, = self.gindex(l, r)
        l += self.num
        r += self.num
        while l < r:
            if l & 1:
                self.lazy[l] += x
                self.data[l] += x
                l += 1
            if r & 1:
                self.lazy[r - 1] += x
                self.data[r - 1] += x
            r >>= 1
            l >>= 1
        for i in ids:
            self.data[i] = self.segfunc(self.data[2 * i], self.data[2 * i + 1]) + self.lazy[i]


    def query(self, l, r):
        """
        [l, r)のsegfuncしたものを得る
        l: index(0-index)
        r: index(0-index)
        """
        *ids, = self.gindex(l, r)
        self.propagates(*ids)

        res = self.ide_ele

        l += self.num
        r += self.num
        while l < r:
            if l & 1:
                res = self.segfunc(res, self.data[l])
                l += 1
            if r & 1:
                res = self.segfunc(res, self.data[r - 1])
            l >>= 1
            r >>= 1
        return res

# 1 ~ Nまで
N, K = getNM()
que = [getList() for i in range(K)]

# 通りの数を求める問題
# dp？
# 組み合わせ？

# goの要素を足して行ってN = 1を達成できればいい
# ただしgoの数が多い
# ナップサックは無理

# 重複あり部分和
# 部分和の通り

# どうすればN - 1の組み合わせができるか
# ソートする？
# 足し合わせ？


dp = [0] * (N + 1)
seg = LazySegmentTree([0] * (N + 1), segfunc, ide_ele)
dp[1] = 1
seg.add(1, 2, 1)

# dpする
for i in range(1, N):
    dp[i] = seg.query(i, i + 1) % mod
    for l, r in que:
        if i + l <= N:
            seg.add(i + l, min(i + r + 1, N + 1), dp[i])
print(seg.query(N, N + 1) % mod)

### FIXED CODE ###

def getN():
    return int(input())
def getNM():
    return map(int, input().split())
def getList():
    return list(map(int, input().split()))
def getArray(intn):
    return [int(input()) for i in range(intn)]
def input():
    return sys.stdin.readline().rstrip()
def rand_N(ran1, ran2):
    return random.randint(ran1, ran2)
def rand_List(ran1, ran2, rantime):
    return [random.randint(ran1, ran2) for i in range(rantime)]
def rand_ints_nodup(ran1, ran2, rantime):
  ns = []
  while len(ns) < rantime:
    n = random.randint(ran1, ran2)
    if not n in ns:
      ns.append(n)
  return sorted(ns)

def rand_query(ran1, ran2, rantime):
  r_query = []
  while len(r_query) < rantime:
    n_q = rand_ints_nodup(ran1, ran2, 2)
    if not n_q in r_query:
      r_query.append(n_q)
  return sorted(r_query)

from sys import exit

import sys
sys.setrecursionlimit(1000000000)
mod = 998244353

#############
# Main Code #
#############

N, K = getNM()
que = [getList() for i in range(K)]

dp = [0] * (N + 1)
dp[1] = 1
dp[2] = -1

for i in range(1, N + 1):
    dp[i] += dp[i - 1]
    dp[i] %= mod
    for l, r in que:
        if i + l <= N:
            dp[i + l] += dp[i]
        if i + r + 1 <= N:
            dp[i + r + 1] -= dp[i]
print(dp[N] % mod)