#include <iostream>
#include <vector>
#include <map>
#include <fstream>
#include <queue>
#include <set>
#include <stack>
#include <deque>
#include <algorithm>
#define x first
#define y second
#define now q.front()
using namespace std;
ifstream fin("cifre4.in");
ofstream fout("cifre4.out");
string s,s2;
int i,j,m,n,o,p,b,ok,t,k,maxi=0,mini=1000000000,x,y;
vector <int> v;
deque <int> stiva;
long long int a,aux;
int dx[]={0,0,1,-1},dy[]={1,-1,0,0};
map <string,string> mymap,mymap2;
char zz;
int main()
{
    fin>>t;
    while(t)
    {
        t--;
        fin>>n>>p;
        a=n;
        i=-1;
        ok=0;
        while(i<=p)
        {
            i++;
            aux=a;
            while(aux)
            {
                if(aux%10==2||aux%10==3||aux%10==5||aux%10==7)
                {
                    o=0;
                }
                else
                {
                   break;
                }
                aux/=10;

            }
            if(!aux)
            {

                ok=1;fout<<a<<'\n';break;
            }
            a+=p;

        }
        if(!ok)
        {
            fout<<-1<<'\n';
        }

    }
    return 0;
}