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

struct Union_find {
	vector<int> par; //親
	vector<int> siz; //根ノードiの木に含まれる要素数。iが根ノード出ない場合無意味な値となる。

	//n要素で初期化
	Union_find(int n) {
		par.resize(n);
		siz.resize(n);
		for(int i = 0;i < n;i++) {
			par[i] = i;
			siz[i] = 1;
		}
	}

	//木の根を求める
	int find(int x) {
		if(par[x] == x) {
			return x;
		}
		else {
			return par[x] = find(par[x]);
		}
	}

	//ｘとｙの属する集合を併合
	void unite(int x,int y) {
		x = find(x);
		y = find(y);
		if(x == y) {
			return;
		}
		if(siz[x] < siz[y]) {
			swap(x,y);
		}
		par[y] = x;
		siz[x] += siz[y];
	}

	//ｘとｙが同じ集合に属するか否か
	bool same(int x,int y) {
		return find(x) == find(y);
	}

	int size(int x) {
		return siz[find(x)];
	}
};

//A,空白,B,改行の順に読み込み（1 <= A,B <= 100）
int main(int argc,char* argv[]) {
    registerValidation(argc,argv);
    int N = inf.readInt(2,100,"N");
    inf.readSpace();
    int K = inf.readInt(1,100000,"K");
    inf.readEoln();
    set<pair<int,int>> edges;
    Union_find uf(N + 1);
    for(int i = 0;i < N - 1;i++) {
        int a = inf.readInt(1,N);
        inf.readSpace();
        int b = inf.readInt(1,N);
        inf.readSpace();
        int c = inf.readInt(1,K);
        inf.readEoln();
        ensuref(a != b,"Tree can't contain loops");
        ensuref(!edges.count({a,b}),"Tree can't contain multiple edges between a pair of vertices");
        edges.insert({a,b});
        edges.insert({b,a});
        ensuref(!uf.same(a,b),"Tree can't contain cycles");
        uf.unite(a,b);
    }
    inf.readEof();
    return 0;
}