#include<cstdio>
int i,j,n,k,t,div[1000001],d,pp;
int main(){
    freopen("divprim.in","r",stdin);
    freopen("divprim.out","w",stdout);


    d=2;
    while(d<=1000001){

        for(i=d;i<=1000001;i+=d)
            div[i]++;
        d++;
        while(div[d]!=0)
            d++;
    }


    scanf("%d",&t);
    for(i=1;i<=t;i++){
        scanf("%d%d",&n,&k);
        pp=0;
        for(j=n;j>=1&&pp==0;j--)
            if(div[j]==k)
                pp=1;
        if(pp==1)
            printf("%d\n",j+1);
        else
            printf("0\n");
    }
    return 0;
}