// Source: https://usaco.guide/general/io

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

#define int long long

signed main() {
    int t=3;
    while(t--){
        int a,b,n;cin>>a>>b>>n;
        int g=a*b/gcd(a,b);
        string s=to_string(g);
        if(s.size()>n){
            cout<<-1<<endl;
        }
        else{
            while(s.size()<n){
                s+='0';
            }    
            cout<<s<<endl;
        }
    }
}