#include <bits/stdc++.h>
using namespace std;
template <typename T>
void out(T x) {
  cout << x << endl;
  exit(0);
}
const int maxn = 1e6 + 5;
int a, b, n;
int ans[maxn];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> a >> b >> n;
  int _a = a;
  int cur = a;
  for (int i = 0; i < n; i++) {
    bool ok = false;
    for (int d = 0; d <= 9; d++) {
      int tmp = 10 * cur + d;
      if (tmp % b == 0) {
        ans[i] = d;
        ok = true;
        break;
      }
    }
    if (!ok) out(-1);
    cur = 0;
  }
  cout << _a;
  for (int i = 0; i < n; i++) {
    cout << ans[i];
  }
  cout << endl;
  return 0;
}
