unittest
{
	assert( [ "4 5" ].parse.expand.solve == 10 );
	assert( [ "7 3" ].parse.expand.solve == 11 );
	assert( [ "1000000000 1000000000" ].parse.expand.solve == 500000000000000000 );
}



import std.conv;
import std.range;
import std.stdio;
import std.typecons;

void main()
{
	stdin.byLineCopy.parse.expand.solve.writeln;
}

auto parse( Range )( Range input )
if( isInputRange!Range && is( ElementType!Range == string ) )
{
	auto hw = input.front.split.to!( long[] );
	return tuple( hw[ 0 ], hw[ 1 ] );
}

auto solve( long h, long w )
{
	return ( ( w + 1 ) / 2 ) * ( ( h + 1 ) / 2 ) + ( w / 2 ) * ( h / 2 );
}
