#!/usr/bin/env python3
import sys

MOD = 998244353  # type: int

def debug(N, st):
    print(*[st.query(i, i+1) for i in range(N)], sep=" ")

def solve(N: int, K: int, L: "List[int]", R: "List[int]"):
    add = lambda a,b: (a+b)%MOD
    st = SegmentTreeLazy([0]*N, 0, 0, add, add, add)
    st.update(0, 1, 1)
    #debug(N, st)
    for i in range(N):
        #debug(N, st)
        v = st.query(i, i+1)
        for l, r in zip(L, R):
            ll, rr = l + i, min(r + i + 1, N)
            if ll >= N:
                continue
            st.update(ll, rr, v)
    return st.query(N-1, N)


# Generated by 1.1.7.1 https://github.com/kyuridenamida/atcoder-tools
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    K = int(next(tokens))  # type: int
    L = [int()] * (K)  # type: "List[int]"
    R = [int()] * (K)  # type: "List[int]"
    for i in range(K):
        L[i] = int(next(tokens))
        R[i] = int(next(tokens))
    print(solve(N, K, L, R))

class SegmentTreeLazy():
    def __init__(self, arr, ti, ei, func, op, merge):
        self.h = (len(arr) - 1).bit_length()
        self.n = 2**self.h
        self.func = func
        self.op = op
        self.merge = merge
        self.ti = ti
        self.ei = ei
        self.val = [ti for _ in range(2 * self.n)]
        for i in range(len(arr)):
            self.val[self.n + i] = arr[i]
        for i in range(1, self.n)[::-1]:
            self.val[i] = self.func(self.val[2 * i], self.val[2 * i + 1])
        self.laz = [ei for _ in range(2 * self.n)]

    def reflect(self, k):
        if self.laz[k] == self.ei:
            return self.val[k]
        return self.op(self.val[k], self.laz[k])

    def propagate(self, k):
        if self.laz[k] == self.ei: return
        self.laz[2 * k] = self.merge(self.laz[2 * k], self.laz[k])
        self.laz[2 * k + 1] = self.merge(self.laz[2 * k + 1], self.laz[k])
        self.val[k] = self.reflect(k)
        self.laz[k] = self.ei

    def thrust(self, k):
        for i in range(1, self.h + 1)[::-1]:
            self.propagate(k >> i)

    def recalc(self, k):
        while k:
            k >>= 1
            self.val[k] = self.func(self.reflect(2 * k), self.reflect(2 * k + 1))

    def update(self, lt, rt, x):
        lt += self.n
        rt += self.n
        vl = lt
        vr = rt
        self.thrust(lt)
        self.thrust(rt - 1)
        while rt - lt > 0:
            if lt & 1:
                self.laz[lt] = self.merge(self.laz[lt], x)
                lt += 1
            if rt & 1:
                rt -= 1
                self.laz[rt] = self.merge(self.laz[rt], x)
            lt >>= 1
            rt >>= 1
        self.recalc(vl)
        self.recalc(vr - 1)

    def query(self, lt, rt):
        lt += self.n
        rt += self.n
        self.thrust(lt)
        self.thrust(rt - 1)
        vl = vr = self.ti
        while rt - lt > 0:
            if lt & 1:
                vl = self.func(vl, self.reflect(lt))
                lt += 1
            if rt & 1:
                rt -= 1
                vr = self.func(self.reflect(rt), vr)
            lt >>= 1
            rt >>= 1
        return self.func(vl, vr)
    

def test():
    import doctest
    doctest.testmod()

if __name__ == '__main__':
    #test()
    main()


Measured memory_bytes: 148156