#include <iostream>
#include <cmath>

#define ll long long

using namespace std;

ll A, B, N, i, l, k, p;

ll lnko(ll a, ll b)
{
    ll r;
    r = a % b;
    while (r)
    {
        a = b;
        b = r;
        r = a % b;
    }

    return b;
}

int main()
{
    k = 3;
    while (k)
    {
        --k;
        cin >> A >> B >> N;

        l = lnko(A, B);
        l = (A * B) / l;


        p = log10(l) + 1;
        if (p > N) cout << -1;
        else
        {
            cout << l;
            for (i = p + 1; i <= N; ++i)
                cout << 0;
        }

        cout << '\n';
    }
    return 0;
}