#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <functional>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
#include <cassert>
#include <cstring>
using namespace std;
typedef long long LL;
typedef complex<double> CMP;

class CubePacking { public:
	int getMinimumVolume(int Ns, int Nb, int L) 
	{
		int m = L*L*L*Nb + Ns;
		int M = L*L*L*Nb + Ns + L*L;
		for(int c=m; c<=M; ++c) // <M should be fine, but just in case...
		{
			for(int p=1; p*p*p<=c; ++p) if( c%p == 0 )
			for(int q=p; p*q*q<=c; ++q) if( c/p%q == 0 )
			{
				int r = c/p/q;
				int nL = (p/L)*(q/L)*(r/L);
				if( Nb <= nL )
					return c;
			}
		}
		assert(false);
		return -1;
	}
};

// BEGIN CUT HERE
#include <ctime>
double start_time; string timer()
 { ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
 { os << "{ ";
   for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
   os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
void verify_case(const int& Expected, const int& Received) {
 bool ok = (Expected == Received);
 if(ok) cerr << "PASSED" << timer() << endl;  else { cerr << "FAILED" << timer() << endl;
 cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
#define END	 verify_case(_, CubePacking().getMinimumVolume(Ns, Nb, L));}
int main(){

CASE(0)
	int Ns = 2; 
	int Nb = 2; 
	int L = 2; 
	int _ = 20; 
END
CASE(1)
	int Ns = 19; 
	int Nb = 1; 
	int L = 2; 
	int _ = 27; 
END
CASE(2)
	int Ns = 51; 
	int Nb = 7; 
	int L = 5; 
	int _ = 950; 
END
CASE(3)
	int Ns = 12345; 
	int Nb = 987; 
	int L = 10; 
	int _ = 999400; 
END
CASE(4)
	int Ns = 1000000000; 
	int Nb = 1000000; 
	int L = 10; 
	int _ = -1; 
END
CASE(5)
	int Ns = 1; 
	int Nb = 1; 
	int L = 1; 
	int _ = 2; 
END
CASE(5)
	int Ns = 1; 
	int Nb = 1; 
	int L = 2; 
	int _ = 12; 
END

}
// END CUT HERE
