pb4

#include<stdio.h>
int main()
{
    int i, a,b,count;
  seive();
while(1)
    {
        scanf("%d %d",&a,&b);
if(a=0 && b==0)
break;

count=0;
for(i=a;i<b;i++)
  {

    if(prime[i]==1)
{
    count++;
}}

    printf("%d",count);}

    return 0;
}