#include <stdio.h>

using namespace std;

FILE*f=fopen("divprim.in","r");
FILE*g=fopen("divprim.out","w");
unsigned long n,j;
int k,i,fl,a[1000000],t;
int main()
{
    for(i=2;i<=1000;i++)
        if(a[i]==0)
            for(j=i+i;j<=1000;j+=i)
                a[j]=a[j]+1;

    fscanf(f,"%d",&t);
    for(i=1;i<=t;i++)
        {
        fl=1;
        fscanf(f,"%lu%d",&n,&k);
        for(j=n;j>2&&fl;j--)
            if(a[j]==k) {fprintf(g,"%lu\n",j);fl=0;}
        if(fl) fprintf(g,"0\n");
        }

    fclose(f);
    fclose(g);
    return 0;
}