#include <bits/stdc++.h>
using namespace std;
int main() {
  int a1, b, n;
  cin >> a1 >> b >> n;
  int temp = 0;
  long long int a = a1;
  while (n-- > 0) {
    temp = 0;
    a *= 10;
    for (int i = 0; i <= 9; i++) {
      if (a % b == 0) {
        cout << a;
        for (int i = 0; i < n; i++) cout << 0;
        n = 0;
        temp = 1;
        break;
      }
      a++;
    }
    if (temp == 0) {
      cout << -1 << endl;
      break;
    }
  }
  return 0;
}
