#include <iostream>

using namespace std;

typedef long long ll;

ll gcd(ll a, ll b){
    if(b == 0){
        return a;
    } else{
        return gcd(b, a % b);
    }
}

int main()
{
    ll t = 3;
    while(t--){
        ll a, b, n;
        cin >> a >> b >> n;

        ll lnko = gcd(a, b);

        ll lkkt = a * b / lnko;

        ll szam = 0;
        ll mas = lkkt;
        while(mas > 0){
            szam++;
            mas /= 10;
        }

        if(szam > n){
            cout << "-1\n";
        } else{
            cout << lkkt;
            for(ll i = szam + 1; i <= n; i++){
                cout << "0";
            }
            cout << "\n";
        }
    }
}