#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <limits.h>
#include <algorithm>
#include <math.h>

using namespace std;
using ll = long long;

ll gcd(ll a, ll b)
{
	ll rem = 1;
	if (a > b) swap(a, b);
	while (rem > 0)
	{
		rem = b % a;
		b = a;
		a = rem;
	}
	return b;
}

int digits(ll x)
{
	int i = 0;
	while (x > 0)
	{
		x /= 10;
		i++;
	}
	return i;
}

int main()
{
	iostream::sync_with_stdio(0);
	cin.tie(0);

	int t = 3;
	while (t--)
	{
		ll a, b, n;
		cin >> a >> b >> n;
		ll lnko = gcd(a, b);
		ll lkkt = a * b / lnko;
		if (digits(lkkt) > n) cout << -1 << '\n';
		else
		{
			cout << lkkt;
			for (int i = 0; i < n-digits(lkkt); i++)
			{
				cout << 0;
			}
			cout << '\n';
		}
	}
}