#include <bits/stdc++.h>
using namespace std;
long long a, b, c;
int n;
vector<int> ans;
int main() {
  scanf("%lld %lld %d", &a, &b, &n);
  c = a % b;
  ans.push_back(a);
  for (int i = 0; i < n; ++i) {
    for (long long j = 0; j < 10; ++j) {
      if (((c * 10L) + j) % b == 0) {
        c = 0;
        ans.push_back(j);
        break;
      }
    }
  }
  if (ans.size() == 1)
    printf("-1");
  else {
    for (int i = 0; i < ans.size(); ++i) cout << ans[i];
  }
  return 0;
}
