#include<iostream>
#include<cmath>
using namespace std;
int main()
{
int a,b,c=0,ile;
cin>>ile;
for(int g=0;g<ile;g++)
{
cin>>b>>a;
int tab[a+1];
for(int i=2;i<=a;i++)
{
tab[i]=1;
}
tab[1]=0;
for(int i=2;i<=sqrt(a);i++)
{
if(tab[i]==1)
for(int j=i+i;j<=a;j=j+i)
{
tab[j]=0;
}
}
for(int i=b;i<=a;i++)
{
if(tab[i]==1) c++;
}
cout<<c<<endl;
c=0;
}
}
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