#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a, b, n;
  string ans = "";
  bool flag = false;
  cin >> a >> b >> n;
  while (n--) {
    if (flag) {
      ans += '0';
    } else {
      for (long long i = 0; i <= 9; i++) {
        if ((a * 10 + i) % b == 0) {
          flag = true;
          a = a * 10 + i;
          ans = to_string(a);
          break;
        }
      }
    }
    if (flag == false) break;
  }
  if (flag)
    cout << ans << endl;
  else
    cout << -1 << endl;
  return 0;
}
