#include <cstdio>

using namespace std;
const int NMAX=1000005;
int c[NMAX];
int main()
{
    freopen("divprim.in","r",stdin);
    freopen("divprim.out","w",stdout);
    int t,n,k,i,j,ok;
    for(i=2; i<=NMAX; i=i+2)
        c[i]=1;
    for(i=3; i<=NMAX; i=i+2)
        if(!c[i])
            for(j=i; j<=NMAX; j=j+i)
                c[j]++;
    scanf("%d",&t);
    for(i=1; i<=t; i++)
    {
        ok=0;
        scanf("%d%d",&n,&k);
        for(j=n; j>=1; j--)
            if(c[j]==k)
            {
                ok=1;
                printf("%d\n",j);
                break;
            }
        if(!ok)
            printf("0\n");
    }
    return 0;
}