#include<cstdio>
#include<cmath>
using namespace std;
int u;
int v[1000005];
void ciur2(int n)
{
  int i,j;
  for(i=2;i<=n;++i)
  {
    if(v[i]==0)
    for(j=i;j<=n;j=j+i)
      v[j]++;
  }
}

int main()
{
    freopen("divprim.in","r",stdin);
    freopen("divprim.out","w",stdout);
    int i,ok,j;

    ciur2(1000005);
    int t,n,k;
    scanf("%d",&t);
    for(i=1; i<=t; ++i)
    {
        scanf("%d%d",&n,&k);
        ok=0;
        for(j=n; j>=1; --j)
            if(v[j]==k)
            {
                ok=1;
                printf("%d\n",j);
                break;
            }
        if(ok==0)
            printf("0\n");
    }
}