#include<stdio.h>
int nd[1000001];
int main() 
{
freopen("divprim.in", "r", stdin);
freopen("divprim.out", "w", stdout);
int i,j,t,k,n;
for(i=2;i<=1000000;i=i+2)
	nd[i]++;
for(i=3;i<=1000001;i++)
	if(nd[i]==0)
		for(j=i;j<=1000001;j=j+i)
			nd[j]++;
		scanf("%d",&t);
		for(j=1;j<=t;j++)
		{
			scanf("%d%d",&n,&k);
			for(i=n;i>=2;i--)
				if(nd[i]==k)
				{
					printf("%d\n",i);
					break;
				}
				if(i==1)
					printf("0\n");
		}
return 0;
}