백준 4948 파이썬

import math

number = [x for x in range(1,246913)]

number.insert(0,1)

for i in range(2,246913):

j=2

while 246912>=i*j:

number[i*j]=1

j+=1

a=int(input())

while a!=0:

count=0

for i in range(a+1,2*a+1):

if number[i]!=1:

count += 1

print(count)

a=int(input())