#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, n;
  cin >> a >> b >> n;
  vector<int> ans(n + 1, -1);
  ans[0] = a;
  int cur_sum = a;
  for (int i = 1; i <= n; i++) {
    bool ok = false;
    for (int j = 0; j < 10; j++)
      if ((cur_sum * 10 + j) % b == 0) {
        ok = true;
        ans[i] = j;
        cur_sum = (cur_sum * 10 + j) % b;
        break;
      }
    if (!ok) {
      cout << "-1";
      break;
    }
  }
  if (ans[n] != -1)
    for (size_t i = 0; i < ans.size(); i++) cout << ans[i];
  cout << endl;
}
