import sys

sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
dij = [(0, 1), (1, 0), (1, 1), (1, -1)]
inf = 10**16
# md = 998244353
md = 10**9+7

from collections import defaultdict

l, r = LI()
to = defaultdict(list)
for i in range(l, r+1):
    for j in range(i+i, r+1, i):
        to[i].append(j)
        to[j].append(i)

def dfs(i):
    stack = [i]
    fin[i] = True
    while stack:
        i = stack.pop()
        for j in to[i]:
            if fin[j]: continue
            fin[j] = True
            stack.append(j)

fin = [False]*(r+1)
ans = 0
for i in range(l, r+1):
    if fin[i]: continue
    dfs(i)
    ans += 1

print(ans-1)