#include <bits/stdc++.h>
using namespace std;
int n, m, k;
int main() {
  while (cin >> n >> m >> k) {
    int flag = 1;
    for (int i = 0; i <= 9; i++) {
      if ((n * 10 + i) % m == 0) {
        flag = 0;
        cout << n << i;
        for (int i = 1; i < k; i++) cout << 0;
        cout << endl;
        break;
      }
    }
    if (flag) cout << "-1" << endl;
  }
}
