def aa(m): c=[] while m!=uf[m]: c.append(m) m=uf[m] for i in c: uf[i]=m return m l,r=map(int,input().split()) uf=[i for i in range(r+1)] for i in range(l,r+1): for j in range(i+i,r+1,i): q,w=aa(i),aa(j) if q!=w: uf[q]=w s=set() for i in range(l,r+1): s.add(aa(i)) print(len(s)-1)