inf=998244353


N,K=map(int,input().split())
SS=[]

for i in range(K):
    s1,s2=map(int,input().split())
    for j in range(s1,s2+1):
        SS.append(j)

SS.sort()

table = [0 for k in range(N-1)] 

for s in SS:
    if s<=N-1:
        table[s-1]+=1
for i in range(N-1):
    if table[i]!=0:
        for s in SS:
            if i+s<N-1:
                table[i+s]+=table[i]
                table[i+s]%=inf
                #print(table,i,s)
            else:
                break
print(table[-1]%inf)
