#include <fstream>

using namespace std;
int v[1000001],i,j,t,k,n;
ifstream fin ("divprim.in");
ofstream fout ("divprim.out");

int main (){

    for (i=2;i<=1000001;i++){
        if (v[i]==0)
            for (j=i;j<=1000001;j+=i)
                v[j]++;
    }
    fin>>t;
    for (i=1;i<=t;i++){
        fin>>n>>k;
        int ok = 0;
        for (j=n-1;j>=1;j--)
            if (v[j] == k){
                ok++;
                fout<<j<<"\n";
                break;
            }
        if (ok == 0)
            fout<<0<<"\n";
    }

    return 0;
}