#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <stack>
using namespace std;

const int MAX_NODE = 5010, INF = 0x3f3f3f3f;

struct Node
{
	vector<Node*> Next;
	int DfsN, Low;
	bool InStack;
}_nodes[MAX_NODE];
int TotNode, TotEdge;
int AnsConIds[MAX_NODE], TempConIds[MAX_NODE];//Con::Connect
int AnsConCnt, TempConCnt;
int CurDfsN;
stack<Node*> St;

void AddEdge(int u, int v, int k)
{
	_nodes[u].Next.push_back(_nodes + v);
	if (k == 2)
		_nodes[v].Next.push_back(_nodes + u);
}

bool CmpArg(int *a, int *b, int n)
{
	for (int i = 1; i <= n; i++)
		if (a[i] != b[i])
			return a[i] < b[i];
	return false;
}

void UpdateAns()
{
	if (TempConCnt >= AnsConCnt)
	{
		sort(TempConIds + 1, TempConIds + TempConCnt + 1);
		if (TempConCnt > AnsConCnt || CmpArg(TempConIds, AnsConIds, AnsConCnt))
		{
			memcpy(AnsConIds, TempConIds, sizeof(TempConIds));
			AnsConCnt = TempConCnt;
		}
	}
}

void PopStack(Node *cur)
{
	TempConCnt = 0;
	Node *temp;
	do {
		temp = St.top();
		temp->InStack = false;
		TempConIds[++TempConCnt] = temp - _nodes;
		St.pop();
	} while (temp != cur);
	UpdateAns();
}

void Dfs(Node *cur)
{
	cur->DfsN = ++CurDfsN;
	cur->Low = cur->DfsN;
	St.push(cur);
	cur->InStack = true;
	int nextCnt = cur->Next.size();
	for (int i = 0; i < nextCnt; i++)
	{
		if (!cur->Next[i]->DfsN)
		{
			Dfs(cur->Next[i]);
			cur->Low = min(cur->Low, cur->Next[i]->Low);
		}
		else if(cur->Next[i]->InStack)
			cur->Low = min(cur->Low, cur->Next[i]->DfsN);
	}
	if (cur->Low == cur->DfsN)
		PopStack(cur);
}

int main()
{
	scanf("%d%d", &TotNode, &TotEdge);
	for (int i = 1; i <= TotEdge; i++)
	{
		int u, v, k;
		scanf("%d%d%d", &u, &v, &k);
		AddEdge(u, v, k);
	}
	CurDfsN = 0;
	for (int i = 1; i <= TotNode; i++)
	{
		if (!_nodes[i].DfsN)
		{
			_printf("from %d:\n", i);
			while (St.size())
				St.pop();
			CurDfsN = 0;
			Dfs(_nodes + i);
		}
	}
	printf("%d\n", AnsConCnt);
	sort(AnsConIds + 1, AnsConIds + AnsConCnt + 1);
	for (int i = 1; i <= AnsConCnt; i++)
		printf("%d ", AnsConIds[i]);
	printf("\n");
	return 0;
}