#include <bits/stdc++.h>
using namespace std;
#define InTheNameOfGod ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
using ll = long long;

const ll maxN = 2e5 + 5;
const ll MOD = 1e9 + 7;

ll lca(ll a, ll b) {
    return (a*b) / __gcd(a, b);
}

ll cnt(ll x) {
    ll ret = 0;
    while (x > 0) {
        ret++;
        x /= 10;
    }
    return ret;
}


int main() {
   InTheNameOfGod;

    ll t = 3;
    //cin >> t;
    while(t--)
    {
        ll a,b,n;
        cin >> a >> b >> n;

        ll temp = lca(a, b);
        ll temp2 = cnt(temp);
        if(temp2 > n) cout << "-1\n";
        else {
            cout << temp;
            for(ll i = 0; i < n-temp2; i++) cout << '0';
            cout << "\n";
        }
    }
    return 0;
}