#include <bits/stdc++.h>
using namespace std;

int main(){
    int t = 3;
    while(t--){
        long long A, B, N;
        cin >> A >> B >> N;
        long long c = A* B / __gcd(A, B);
        string s = to_string(c);
        if(s.length() > N){
            cout << -1;
        }
        else{
            while(s.length() < N){
                s += "0";
            }
            cout << s;
        }
        cout << endl;
    }
}