#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  ll a, b, c;
  cin >> a >> b >> c;
  for (ll i = 0; i < 10; i++) {
    if (((a * 10) + i) % b == 0) {
      cout << a << i;
      cout << string(c - 1, '0') << endl;
      return 0;
    }
  }
  cout << -1 << endl;
}
