n,k=map(int,input().split())
xy = [map(int, input().split()) for _ in range(k)]
x, y = [list(i) for i in zip(*xy)]

slist=[]
for j in range(k):
    jlist=list(range(x[j],y[j]+1))
    slist.extend(jlist)

alist=[1]
blist=[0]*(n-1)
alist.extend(blist)
for r in range(n):
    for sa in slist:
        if r+sa<=n-1:
            alist[r+sa]+=alist[r]

ans=alist[n-1]
answer=ans%998244353
print(answer)