import java.io.*;
import hsa.Console;
import java.util.StringTokenizer;

// The "Rhombus" class.
public class Four
{
    public static void main (String[] args) throws IOException
    {

	// Open up the input and output file for IO purpose
	FileReader inFile = new FileReader ("DATA5.txt");
	FileWriter outFile = new FileWriter ("OUT5.txt");

	// Link the input and output file for
	BufferedReader in = new BufferedReader (inFile);
	BufferedWriter out = new BufferedWriter (outFile);

	// String e;
	String line;
	String temp;
	int largest = 0;
	boolean even;
	boolean All2 = true;
	boolean Zero = true;
	boolean Four = true;


	// Keep reading as long as not end of file (eof)
	while ((line = in.readLine ()) != null)
	{
	    int num = Integer.parseInt (line);
	    int[] num1 = new int [num];
	    int[] num2 = new int [num];

	    for (int count = 0 ; count < num ; count++)
	    {

		temp = in.readLine ();
		StringTokenizer info = new StringTokenizer (temp);
		String temp1 = info.nextToken ();
		String temp2 = info.nextToken ();
		num1 [count] = Integer.parseInt (temp1);
		num2 [count] = Integer.parseInt (temp2);

	    }

	    for (int count = 0 ; count < num ; count++)
	    {
		if (num1 [count] > largest)
		{
		    largest = num1 [count];
		}
		if (num2 [count] > largest)
		{
		    largest = num2 [count];
		}
	    }




	    if (largest % 2 != 0)
	    {
		even = false;
	    }
	    else
	    {
		even = true;
	    }


	    int[] edges = new int [largest];

	    for (int i = 0 ; i < num ; i++)
	    {
		int col1 = num1 [i];
		int col2 = num2 [i];

		if (col1 != col2)
		{
		    edges [col1 - 1]++;
		    edges [col2 - 1]++;
		}

	    }



	    for (int j = 0 ; j < largest ; j++)
	    {

		if (edges [j] > 2)
		{
		    All2 = false;
		}
		if (edges [j] > 0)
		{
		    Zero = false;
		}
		if (edges [j] > 3)
		{
		    Four = false;
		}


	    }
	    if (Zero == true)
	    {
		out.write ("1");
		out.newLine ();
	    }
	    else if (even == true && All2 == true)
	    {
		out.write ("2");
		out.newLine ();
	    }
	    else if (even == false && All2 == true)
	    {
		out.write ("3");
		out.newLine ();
	    }
	    else if (even == false && Four == false)
	    {
		out.write ("0");
		out.newLine ();
	    }
	    else if (even == true && Four == false)
	    {
		out.write ("4");
		out.newLine ();
	    }



	}

	out.flush ();
	out.close ();


    }




}


// main method
// End of Class