Untitled

//_za*mita_
#include <bits/stdc++.h>
using namespace std;
int a[105], cnt = 0;
int main (){
    int d, k;
    while (cin >> d >> k){
        string res="";

        if (k == 1){
        cout << d << endl;
        continue;
        }

        int i = 1, q;
        a[1] = d;

        bool check = false;


        while (check == false){
        res = char(a[i]+'0') + res;
        q = a[i]*k + cnt;
        i++;
        a[i] = q%10;
        cnt  = q/10;
        if (a[i] == d && cnt == 0) check = true;
        }

        if (a[i-1] == 0) cout << -1 << "\n";
        else cout << res <<"\n";
    }
}