class Binary_Indexed_Tree:
    def __init__(self, n):
        """
        :param n: 最大の要素数
        """
        self.n = n
        self.tree = [0] * (n + 1)
        self.depth = n.bit_length() - 1

    def sum(self, i):
        """ 区間[0,i) の総和を求める """
        s = 0
        i -= 1
        while i >= 0:
            s += self.tree[i]
            i = (i & (i + 1)) - 1
        return s

    def built(self, array):
        """ array を初期値とするBITを構築 """
        for i, a in enumerate(array):
            self.add(i, a)

    def add(self, i, x):
        """ i 番目の要素に x を足す """
        while i < self.n:
            self.tree[i] += x
            i |= i + 1

    def get(self, i, j):
        """ 部分区間和 [i, j) """
        if i == 0:
            return self.sum(j)
        return self.sum(j) - self.sum(i)

    def lower_bound(self, x, equal=False):
        """ (a0+a1+...+ai < x となる最大の i, その時の a0+a1+...+ai )
             a0+a1+...+ai <= x としたい場合は equal = True
             二分探索であるため、ai>=0 を満たす必要がある"""
        sum_ = 0
        pos = -1  # 1-indexed の時は pos = 0
        if equal:
            for i in range(self.depth, -1, -1):
                k = pos + (1 << i)
                if k < self.n and sum_ + self.tree[k] <= x:  # 1-indexed の時は k <= self.n
                    sum_ += self.tree[k]
                    pos += 1 << i
        else:
            for i in range(self.depth, -1, -1):
                k = pos + (1 << i)
                if k < self.n and sum_ + self.tree[k] < x:  # 1-indexed の時は k <= self.n
                    sum_ += self.tree[k]
                    pos += 1 << i

        return pos, sum_

    def __getitem__(self, i):
        """ [a0, a1, a2, ...] """
        return self.get(i, i + 1)

    def __iter__(self):
        """ [a0, a1, a2, ...] """
        for i in range(self.n):
            yield self.get(i, i + 1)

    def __str__(self):
        text1 = " ".join(["element:            "] + list(map(str, self)))
        text2 = " ".join(["cumsum(1-indexed):  "] + list(str(self.sum(i)) for i in range(1, self.n + 1)))
        return "\n".join((text1, text2))


mod = 998244353
n, k = map(int, input().split())
a = [list(map(int, input().split())) for _ in range(k)]
for i in range(k):
    a[i][0] -= 1
b = Binary_Indexed_Tree(n)
dp = [0] * n
dp[0] = 1
b.add(0, 1)
for i in range(1, n):
    for l, r in a:
        dp[i] += b.get(max(0, i - r), max(0, i - l))
    dp[i] %= mod
    b.add(i, dp[i])
print(dp[-1])
