def main():
    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)


main()