/* TriangleEasy (SRM 693, D2, 250 from Topcoder).
   James S. Plank
   Sat Sep 17 11:10:03 EDT 2016
 */


#include <string>
#include <vector>
#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;

class TriangleEasy
{
    public:
        int find(int n, vector <int> x, vector <int> y);
};

int TriangleEasy::find(int n, vector <int> x, vector <int> y)
{
    int i, j, k;
    vector < vector <int> > A;
    int edges_needed;

    /* First, create the adjacency matrix. For each x[i]/y[i], I put two
       entries into A -- one for the edge from x[i] to y[i], and one for
       the edge from y[i] to x[i]. */

    A.resize(n);
    for (i = 0; i < A.size(); i++) A[i].resize(n, 0);

    for (i = 0; i < x.size(); i++) {
        A[x[i]][y[i]] = 1;
        A[y[i]][x[i]] = 1;
    }

    /* Now enumerate all possible i, j and k. */

    edges_needed = 3;

    for (i = 0; i < A.size(); i++) {
        for (j = 0; j < A.size(); j++) {
            for (k = 0; k < A.size(); k++) {

                /* Do the tests outlined in the notes, to figure out how
                   many edges are needed for the triangle i,j,k, and
                   if that's less then the current best, then update
                   the current best. */

                if (A[i][j] && A[j][k] && A[k][i]) return 0;
                if (A[i][j] && A[j][k] && edges_needed > 1) edges_needed = 1;
                if (A[i][j] && edges_needed > 2) edges_needed = 2;
            }
        }
    }
    return edges_needed;
}