#include<stdio.h>
int main(){
	int t,n,k,i,j,q,p,d,s,m=0;
	freopen("divprim.in","r",stdin);
	freopen("divprim.out","w",stdout);
	scanf("%d",&t);
	for(i=0;i<t;++i){
		scanf("%d",&n);
		scanf("%d",&k);
		m=0;
		for(j=2;j<=n;++j){
			s=0;
			for(q=2;q<=j;++q){
				p=1;
				d=2;
				while(p && d*d<=q)
					if(q%d==0)
						p=0;
					else
						d++;
				if(p==1 && j%q==0)
					s++;
			}
			if(k==s)
				m=j;
			if(k<s && m==j)
				m=0;
		}
		printf("%d\n",m);
	}
	fclose(stdin);
	fclose(stdout);
	return 0;
}