import numpy as np

N, K = map(int, input().split())

D = []

for _ in range(K):
    L, R = map(int, input().split())

    for i in range(L, R+1):
        D.append(i)

D.sort()

dp = np.zeros(300000)
dp[1] = 1

for d in D:
    for i in range(1, N//d):
        dp += np.roll(dp, i * d)
    dp %= 998244353

print(int(dp[N]))