static void Main(string[] args)
{
int pieces = int.Parse(Console.ReadLine());
string[] temp = new string[pieces];
int left = 0;
int right = 0;
for (int i = 0; i < pieces; i++)
{
temp[i] = Console.ReadLine();
left += int.Parse(temp[i][0].ToString());
right += int.Parse(temp[i][2].ToString());
}
bool finish = false;
if (left % 2 == 0 && right % 2 == 0)
Console.WriteLine(0);
else
{
for (int i = 0; i < temp.Length; i++)
{
int resLeft = left;
int resRight = right;
resLeft -= int.Parse(temp[i][0].ToString());
resLeft += int.Parse(temp[i][2].ToString());
resRight -= int.Parse(temp[i][2].ToString());
resRight += int.Parse(temp[i][0].ToString());
if (resLeft % 2 == 0 && resRight % 2 == 0)
{
finish = true;
break;
}
}
if (finish)
Console.WriteLine(1);
else
Console.WriteLine(-1);
}
}
