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