static public void Main()
{
int source = int.Parse(Console.ReadLine()); // price of chocolate
int dest = int.Parse(Console.ReadLine()); // number of wrapers per chocolate
ChessCell source_cc = GetChessMapping(source);
ChessCell dest_cc = GetChessMapping(dest);
Console.WriteLine(GetMovesCount(source_cc, dest_cc));
}
static int GetMovesCount(ChessCell s, ChessCell d)
{
if (s.row == d.row && s.col== d.col)
return 0;
// white can't reach black and black can't white
if ((s.row + s.col) % 2 != (d.row + d.col) % 2)
return -1;
// d1
if (d.row - s.row == d.col - s.col)
return 1;
// d2
if (d.row - s.row == s.col-d.col)
return 1;
return 2;
}
static int GetMovesCount(ChessCell s, ChessCell d)
{
if (s.row == d.row && s.col == d.col)
{
return(0);
}
// white can't reach black and black can't white
if ((s.row + s.col) % 2 != (d.row + d.col) % 2)
{
return(-1);
}
// d1
if (d.row - s.row == d.col - s.col)
{
return(1);
}
// d2
if (d.row - s.row == s.col - d.col)
{
return(1);
}
return(2);
}