#include <fstream>

using namespace std;
ifstream in("divprim.in");
ofstream out("divprim.out");
int c[1000005];
int main()
{
    int t,n,k,a,b,i;
    in>>t;
    for(a=2; a<=1000000; a=a+2)
            c[a]=1;
        for(a=3; a<=1000000; a=a+2)
            if(!c[a])
                for(b=a; b<=1000000; b=b+a)
                    c[b]++;
    for(i=1; i<=t; i++)
    {
        in>>n>>k;
        
        for(a=n; a>=1; a--)
            if(c[a]==k)
            {
                out<<a<<"\n";
                a=0;
            }
        if(a==0)
            out<<0<<"\n";
            
        
    }
    return 0;
}