#include <cstdio>
using namespace std;

int ciur[1000002],t,n,k,Max;
bool prime[1000002];
struct kapa{
    int v[1000002],p;
}div[9];
int main()
{
	freopen("divprim.in","r",stdin);
	freopen("divprim.out","w",stdout);
	for(int d=2;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++;}
    }
	scanf("%d",&t);
	for(int i=1;i<=t;++i)
    {
        scanf("%d%d",&n,&k);
        Max=0;
        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;
}