#include <bits/stdc++.h>
using namespace std;
int a, b, n, ans[100005];
int main() {
  cin >> a >> b >> n;
  int mod = a % b;
  bool cut = false;
  for (int i = 1; i <= n; i++) {
    ans[i] = -1;
    for (int k = 0; k <= 9; k++)
      if ((mod * 10 + k) % b == 0) {
        ans[i] = k;
        mod = 0;
        break;
      }
    if (ans[i] == -1) {
      cut = true;
      break;
    }
  }
  if (cut)
    printf("-1\n");
  else {
    printf("%d", a);
    for (int i = 1; i <= n; i++) printf("%d", ans[i]);
    printf("\n");
  }
  return 0;
}
