#include <bits/stdc++.h>
const long double eps = 1e-12;
using namespace std;
void solve() {
  long long int a, b, n;
  cin >> a >> b >> n;
  bool ok = true;
  int k = min<long long int>(5, n);
  n -= 5;
  while (ok) {
    if (k > 0) {
      ok = false;
      for (int i = 0; i < 10; i++) {
        if ((a * 10 + i) % b == 0) {
          a = (a * 10 + i);
          ok = true;
          k--;
          break;
        }
      }
    } else {
      break;
    }
  }
  if (k == 0 || a % b == 0) {
    cout << a;
    for (int i = 0; i < n + k; i++) {
      cout << 0;
    }
  } else {
    cout << -1;
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  cout << fixed << setprecision(12);
  int t = 1;
  for (int i = 0; i < t; i++) {
    solve();
  }
  return 0;
}
