IMPA/p696/p696.cpp

#include <iostream>
#include <cmath>

using namespace std;


int main()
{
	int a, b, max_n;

	while(cin >> a >> b)
	{
		if(!a && !b)
			break;

		if(!a || !b)
		{
			max_n = 0;
		}
		else if(a == 1 || b == 1)
		{
			max_n = a*b;
			
		}
		else if(a == 2 || b == 2)
		{
			max_n = (max(a,b)/4) * 4;
			max_n += max(a,b)%4 > 0 ? 2 : 0;
			max_n += max(a,b)%4 > 1 ? 2 : 0;
		}
		else
		{
			max_n = ceil(a * b/2.0);
		}

					cout << max_n << " knights may be placed on a " << a << " row " << b << " column board." << endl;

	}
	
	return 0;
}