#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, n;
  cin >> a >> b >> n;
  if (n == 0 || a == 0) {
    cout << a << endl;
  } else {
    int i = 0;
    while (i < 10) {
      if ((10 * a + i) % b == 0) {
        a = 10 * a + i;
        break;
      }
      i++;
    }
    if (i == 10) {
      cout << -1 << endl;
    } else {
      string s = to_string(a);
      n = n - 1;
      while (n--) {
        s += "0";
      }
      cout << s << endl;
    }
  }
}
