#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 100000 + 9;
int num[MAX_N];
int main() {
  int N, M, T;
  int a, b, c;
  while (scanf("%d%d%d", &a, &b, &c) != EOF) {
    int ans = 0;
    int temp;
    for (int i = 0; i < 10; i++) {
      if ((a * 10 + i) % b == 0) {
        ans = 1;
        temp = i;
      }
    }
    if (ans == 0)
      printf("-1\n");
    else {
      printf("%d", a);
      printf("%d", temp);
      for (int i = 1; i < c; i++) printf("0");
      printf("\n");
    }
  }
  return 0;
}
