def resolve():
    n, k = map(int, input().split())
    mod = 998244353
    dp = [0] * (2*n)
    imos = [0] * (2*n)
    lr = []
    for i in range(k):
        l, r = map(int, input().split())
        lr.append((l, r+1))
    for l, r in lr:
        imos[l] = 1
        imos[r] = -1
    now = 0
    for i in range(1, n):
        now += imos[i]
        now %= mod
        dp[i] = now
        for l, r in lr:
            imos[min(i+l, n+2)] += now
            imos[min(i+r, n+2)] += -1*now
    print(dp[n-1]%mod)


resolve()