#include <bits/stdc++.h>
using namespace std;
long long mod(long long u, long long m) {
  long long res = 1;
  for (long long i = 1; i <= u; i++) res = (10ll * res) % m;
  return res;
}
long long getu(long long o) {
  if (o == 0) return 1;
  long long cnt = 0;
  while (o) {
    o /= 10ll;
    cnt++;
  }
  return cnt;
}
int main() {
  long long a, b, c;
  cin >> a >> b >> c;
  long long t = b - (mod(c, b) * a) % b;
  if (t == b) t = 0;
  long long s = getu(t);
  if (c - s < 0) {
    cout << -1;
  } else {
    cout << a;
    for (long long i = 0; i < c - s; i++) printf("0");
    cout << t;
  }
  cout << endl;
  return 0;
}
