# -*- coding: utf-8 -*-
import bisect
import heapq
import math
import random
from collections import Counter, defaultdict, deque
from decimal import ROUND_CEILING, ROUND_HALF_UP, Decimal
from fractions import Fraction
from functools import lru_cache, reduce
from itertools import combinations, combinations_with_replacement, product, permutations, accumulate
from operator import add, mul, sub, itemgetter, attrgetter


import sys
sys.setrecursionlimit(10**6)
# readline = sys.stdin.buffer.readline
readline = sys.stdin.readline

INF = 1 << 60


def read_int():
    return int(readline())


def read_int_n():
    return list(map(int, readline().split()))


def read_float():
    return float(readline())


def read_float_n():
    return list(map(float, readline().split()))


def read_str():
    return readline().strip()


def read_str_n():
    return readline().strip().split()


def ep(*args):
    print(*args, file=sys.stderr)


def mt(f):
    import time

    def wrap(*args, **kwargs):
        s = time.perf_counter()
        ret = f(*args, **kwargs)
        e = time.perf_counter()

        ep(e - s, 'sec')
        return ret

    return wrap


@mt
def slv(N, K, LR):
    M = 998244353
    @lru_cache(maxsize=None)
    def f(i):
        if i == N:
            ret = 1
        elif i > N:
            ret = 0
        else:
            ret = 0
            for l, r in LR:
                for d in range(l, r+1):
                    if i+d <= N:
                        ret += f(i+d)
                        ret %= M
                    else:
                        break
        return ret

    return f(1)

def main():
    N, K = read_int_n()
    LR = [read_int_n() for _ in range(K)]
    print(slv(N, K, LR))

    # N = 2 * (10**5)
    # p = [random.randint(1, N) for _ in range(20)]
    # p.sort(reverse=True)
    # LR = []
    # K = 10
    # for i in range(1, 11):
    #     LR.append([2*i-1, 2*i])
    # LR.sort()
    # LR[0][0] = 1
    # print(N, K, LR)

    # print(slv(N, K, LR))



if __name__ == '__main__':
    main()
