#include <bits/stdc++.h>
using namespace std;
time_t start = clock();
long long gcd(long long tank, long long garry) {
  if (garry == 0)
    return tank;
  else
    return gcd(garry, tank % garry);
}
long long lcm(long long rudik, long long jay) {
  return rudik * jay / gcd(rudik, jay);
}
long long kat(long long psih, long long sklet) {
  long long takyrlar = 1;
  for (int malow = 0; malow < sklet; malow++) takyrlar *= psih;
  return takyrlar;
}
long long fac(long long buz) {
  long long lal = 1;
  for (int towshan = 2; towshan <= buz; towshan++) lal *= towshan;
  return lal;
}
int a, b, n;
int main() {
  scanf("%d %d %d", &a, &b, &n);
  for (int i = 0; i < 10; i++)
    if ((a * 10 + i) % b == 0) {
      printf("%d%d", a, i);
      for (int j = 0; j < n - 1; j++) printf("0");
      return 0;
    }
  printf("-1");
}
