#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, n, ad = 0;
  cin >> a >> b >> n;
  a *= 10;
  int ok = true;
  for (int i = 0; i < 10; i++) {
    if ((a + i) % b == 0) {
      ad = i;
      ok = false;
    }
  }
  if (ok) {
    cout << "-1\n";
    return 0;
  }
  a += ad;
  cout << a;
  for (int i = 1; i < n; i++) cout << "0";
  cout << endl;
  return 0;
}
