l,r=map(int,input().split())
if l==1:
    print(0)
    exit()
import numpy as np
from scipy.sparse import csr_matrix
from scipy.sparse.csgraph import minimum_spanning_tree
def make_divisors(n):
    divisors = []
    global l
    for i in range(1, int(n**0.5)+1):
        if n % i == 0:
            if l<=i:
                divisors.append(i)
            if i != n // i and l<=n//i:
                divisors.append(n//i)
    return divisors
d=[]
p=[]
q=[]

for i in range(l,r+1):
    ll=make_divisors(i)
    for m in ll:
        for j in range(m,i,m):
            p.append(i)
            q.append(j)
            d.append(0)
    if i!=l:
        p.append(i)
        q.append(i-1)
        d.append(1)

n=r+1
graph=csr_matrix((d,(p,q)),shape=(n,n))
tree = minimum_spanning_tree(graph,overwrite = True).astype(int)
print(tree.sum())