N, K  = map(int, input().split())
L = [list(map(int, input().split())) for _ in range(K)]
S = set()
for l in L:
  S = S|set([i for i in range(l[0], l[1]+1)])
DP = [0]*N
DP[0]=1
for i in range(1, N):
  for j in S:
    if i>=j:
      DP[i] += DP[i-j]
      DP[i] %= 998244353
print(DP[-1])