#include <cstdio>
#include <bitset>
using namespace std;
char v[1000005];
int main()
{
    freopen("divprim.in","r",stdin);
    freopen("divprim.out","w",stdout);
    int t , n , k , i, j;
    for(i=2;i<=1000000;i+=2)v[i]=1;
    for(i=3;i<=1000000;i+=2)
        if(!v[i])
        for(j=i;j<=1000000;j+=i)v[j]++;
    scanf("%d",&t);
    for(i=1;i<=t;i++)
    {
        scanf("%d%d",&n,&k);
        for(j=n;j>0;j--)
            if(v[j]==k)
            {printf("%d\n",j);
        break;}
        if(j==0)printf("0\n");
    }
    return 0;
}