n, k = map(int, input().split())
s = set()
# lr = []
for _ in range(k):
    l, r = map(int, input().split())
    # lr.append(tuple(map(int, input().split())))
    for tmp in range(l, r+1):
        s.add(tmp)
mod = 998244353

dp = [0]*n
dp[0] = 1

for i in range(1, n):
    # for l, r in lr:
    for ss in s:
        if i-ss >= 0:
            dp[i] += dp[i-ss]
    dp[i] %= mod

print(dp[-1]%mod)