#include <bits/stdc++.h>
using namespace std;
void fs(int &number) {
  bool negative = false;
  register int c;
  number = 0;
  c = getchar();
  if (c == '-') {
    negative = true;
    c = getchar();
  }
  for (; (c > 47 && c < 58); c = getchar()) {
    number = number * 10 + c - 48;
  }
  if (negative) {
    number *= -1;
  }
}
int a, b, n;
string output;
int main() {
  fs(a);
  fs(b);
  fs(n);
  int MOD = a % b;
  bool can;
  output = to_string(a);
  for (int i = 0; i < n; i++) {
    can = 0;
    for (int j = 0; j < 10; j++) {
      if ((MOD * 10 + j) % b == 0) {
        output += char(j + '0');
        MOD = (MOD * 10 + j) % b;
        can = 1;
        break;
      }
    }
    if (!can) {
      break;
    }
  }
  if (can) {
    printf("%s\n", output.c_str());
  } else {
    printf("-1\n");
  }
  return 0;
}
