#include<stdio.h>
int main(){
	long long n,k,i,j,t,s,ok,q,d,p;
	freopen("divprim.in","r",stdin);
	freopen("divprim.out","w",stdout);
	scanf("%lld",&t);
	for(i=0;i<t;++i){
		scanf("%lld",&n);
		scanf("%lld",&k);
		ok=1;
		for(j=n;j>=0 && ok;--j){
			s=0;
			if(j%2==0)
				s++;
			for(q=3;q<=j;q+=2){
				p=1;
				d=3;
				if(q%2==0)
					p=0;
				else
					while(p && d*d<=q)
						if(q%d==0)
							p=0;
						else
							d+=2;
				if(j%q==0 && p)
					s++;
			}
			if(k==s){
				printf("%lld\n",j);
				ok=0;
			}
		}
		if(ok!=0)
			printf("0\n");
	}
	fclose(stdin);
	fclose(stdout);
	return 0;
}