#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long a, b, c;
  cin >> a >> b >> c;
  a *= 10;
  long long q = 0;
  for (long long j = 0; j <= 9; j++) {
    a += j;
    if (a % b == 0) {
      q = 1;
      break;
    } else
      a -= j;
  }
  if (q == 0) {
    cout << -1 << endl;
    return 0;
  }
  cout << a;
  for (long long i = 0; i < c - 1; i++) cout << 0;
}
