#include <cstdio>
using namespace std;
int ciur[1000002],t,n,k,Max;
bool prime[1000002];
struct kapa{
int v[1000002],p,Min;
}div[9];
int main()
{
freopen("divprim.in","r",stdin);
freopen("divprim.out","w",stdout);
for(int d=2;d*d<=1000002;++d)
{
if(prime[d]==0)
{
ciur[d]++;
for(int j=d*2;j<=1000002;j+=d)prime[j]=1,ciur[j]++;
}
if(ciur[d]<=7){div[ciur[d]].v[div[ciur[d]].p]=d;div[ciur[d]].p++;if(div[ciur[d]].Min==0)div[ciur[d]].Min=d;}
}
scanf("%d",&t);
for(int i=1;i<=t;++i)
{
scanf("%d%d",&n,&k);
Max=0;
if(div[k].Min<=n)
for(int j=div[k].p-1;j>=0;--j)
if(div[k].v[j]<=n){Max=div[k].v[j];break;}
printf("%d\n",Max);
}
fclose(stdin);fclose(stdout);
return 0;
}