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

struct UnionFind {
  vector< int > data;
 
  UnionFind(int sz) {
    data.assign(sz, -1);
  }
 
  bool unite(int x, int y) {
    x = find(x), y = find(y);
    if(x == y) return (false);
    if(data[x] > data[y]) swap(x, y);
    data[x] += data[y];
    data[y] = x;
    return (true);
  }
 
  int find(int k) {
    if(data[k] < 0) return (k);
    return (data[k] = find(data[k]));
  }
 
  int size(int k) {
    return (-data[find(k)]);
  }
};

int main(int argc, char* argv[]){
    const int MIN_N = 3;
    const int MAX_N = 100000;
    const int MIN_K = 2;
    const int MAX_K = 6;

    registerValidation(argc, argv);
    int n = inf.readInt(MIN_N, MAX_N);
    inf.readSpace();
    int k = inf.readInt(MIN_K, MAX_K);
    inf.readEoln();
    UnionFind uf(n);
    for (int i = 0; i < n; i++)
    {
        int a = inf.readInt(1, n);
        inf.readSpace();
        int b = inf.readInt(1, n);
        inf.readEoln();
        ensuref(a != b, "a and b should not be equal");
        uf.unite(a - 1, b - 1);
    }
    ensuref(uf.size(0) == n, "the graph should be connected");
    inf.readEof();
    return 0;
}