#include "testlib.h"
#include <bits/stdc++.h>
using namespace std;

const int MIN_N = 1;
const int MAX_N = 1e5;
const int MIN_K = 1;
const int MAX_K = 6;

struct UnionFind {
  int num;
  vector<int> rs, ps;
  UnionFind(int n) : num(n), rs(n, 1), ps(n, 0) {
    iota(ps.begin(), ps.end(), 0);
  }
  int find(int x) { return (x == ps[x] ? x : ps[x] = find(ps[x])); }
  bool same(int x, int y) { return find(x) == find(y); }
  void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y)
      return;
    if (rs[x] < rs[y])
      swap(x, y);
    rs[x] += rs[y];
    ps[y] = x;
    num--;
  }
  int size(int x) { return rs[find(x)]; }
  int count() const { return num; }
};

signed main(int argc, char *argv[]) {
  registerValidation(argc, argv);
  int N = inf.readInt(MIN_N, MAX_N, "N");
  inf.readSpace();
  inf.readInt(MIN_K, MAX_K, "K");
  inf.readEoln();

  UnionFind uf(N);
  for (int i = 0; i < N; i++) {
    int a = inf.readInt(1, N, "a_i");
    inf.readSpace();
    int b = inf.readInt(1, N, "b_i");
    inf.readEoln();
    uf.unite(a - 1, b - 1);
  }
  ensure(uf.count() == 1);
  inf.readEof();
  return 0;
}