#include <iostream>
#include <cstdio>
#include <vector>
#define _USE_MATH_DEFINES
#include <math.h>
#include <cstring>
#include <numeric>
#include <algorithm>
#include <stdlib.h>
#include <functional>
#include <string>
#include <array>
#include <map>
#include <queue>
#include <limits.h>
#include <set>
#include <stack>
#include <random>
#include <complex>
#include <unordered_map>
#include <nmmintrin.h>
#include <chrono>
const double EPS = 1e-8;
#define Scan(a) int a;scanf("%d", &a);
#define ScanS(a) char a[500];scanf("%s", a);
#define rep(i,s,n) for(int i = (s); (n) > i; i++)
#define REP(i,n) rep(i,0,n)
#define RANGE(x,a,b) ((a) <= (x) && (x) <= (b))
#define DUPLE(a,b,c,d) (RANGE(a,c,d) || RANGE(b,c,d) || RANGE(c,a,b) || RANGE(d,a,b))
#define INCLU(a,b,c,d) (RANGE(a,c,d) && (b,c,d))
#define PW(x) ((x)*(x))
#define ALL(x) (x).begin(), (x).end()
#define MODU 1000000007
#define bitcheck(a,b)   ((a >> b) & 1LL)
#define bitset(a,b)      ( a |= (1LL << b))
#define bitunset(a,b)    (a &= ~(1LL << b))
#define MP(a,b) make_pair((a),(b))
#define Manh(a,b) (abs((a).first-(b).first) + abs((a).second - ((b).second))
#define pritnf printf
#define scnaf scanf
#define itn int
#ifdef _MSC_VER
#define __builtin_popcount _mm_popcnt_u32
#define __builtin_popcountll _mm_popcnt_u64
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

ll gcd(ll a, ll b) {
	if (b == 0) return a;
	return gcd(b, a%b);
}
template<typename A, size_t N, typename T>
void Fill(A(&array)[N], const T &val) {
	std::fill((T*)array, (T*)(array + N), val);
}

pii Dir[8] = {
	{ 0 ,1 },{ -1 ,0 },{ 1 ,0 },{ 0 ,-1 },
	{ 1 ,1 },{ 1 ,-1 },{ -1 ,1 },{ -1 ,-1 }
};


pii operator+(pii obj, pii obj2) {
	return MP(obj.first + obj2.first, obj.second + obj2.second);
}
pii operator-(pii obj, pii obj2) {
	return MP(obj.first - obj2.first, obj.second - obj2.second);
}
class Graph {
public:
	int vn;
	int sumcost = 0;
	vector<vector<pii>> g;

	Graph(int n) {
		vn = n;
		g.resize(n);
	}
	virtual void con(int a, int b, int w) = 0;
	int getWeight(int f, int t) {
		auto itr = lower_bound(ALL(g[f]), make_pair(t, INT_MIN));
		if (itr != g[f].end())
			return itr->second;
		return INT_MIN;
	}
	int Costsum() {
		return sumcost;
	}
	void scan(int edcount, bool oindexed, bool w) {
		REP(i, edcount) {
			int a, b, c = 1;
			scanf("%d %d", &a, &b);
			if (w)scanf("%d", &c);
			con(a - oindexed, b - oindexed, c);
		}
	}
};
class BiDGraph : public Graph {//無向
public:
	BiDGraph(int n) : Graph(n) {}

	void con(int a, int b, int w = 1) {
		g[a].push_back({ b, w });
		g[b].push_back({ a, w });
		sumcost++;
	}
};
class DGraph : public Graph {//有向
public:
	DGraph(int n) : Graph(n) {}
	void con(int a, int b, int w = 1) {
		g[a].push_back({ b,w });
		sumcost++;
	}
};

struct UnionFind {
	vector<int> data;
	UnionFind(int size) : data(size, -1) { }
	bool unionSet(int x, int y) { //ｘの入ってる集合と yの入ってる集合を併合
		x = root(x); y = root(y);
		if (x != y) {
			if (data[y] < data[x]) swap(x, y);
			data[x] += data[y]; data[y] = x;
		}
		return x != y;
	}
	bool findSet(int x, int y) { //xとyが同じ集合に入っているかどうかを判定
		return root(x) == root(y);
	}
	int root(int x) {
		return data[x] < 0 ? x : data[x] = root(data[x]);
	}
	bool isroot(int x) {
		return data[x] < 0;
	}
	int size(int x) {
		return -data[root(x)];
	}
};
int main() {
	int n, r;
	cin >> n >> r;

	BiDGraph g(n);
	g.scan(r,1,1);



	vector<vector<int>> dis(n,vector<int>(n, -1));

	REP(cc, n) {
		vector<bool> al(n);
		priority_queue<pii, vector<pii>, greater<pii>> pq;

		pq.push({ 0, cc });

		while (pq.size()) {
			auto cur = pq.top();
			pq.pop();
			if (al[cur.second]) continue;
			dis[cc][cur.second] = cur.first;
			dis[cur.second][cc] = cur.first;
			al[cur.second] = 1;
			for (auto itr : g.g[cur.second]) {
				if (!al[itr.first]) {
					pq.push({cur.first + itr.second, itr.first});
				}
			}


		}

	}

	vector<bool> used(n);
	vector<vector<bool>> al(n,vector<bool>(n));

	int Max = 0;

	REP(i,n)
		REP(j, n) {
		Max = max(Max, dis[i][j]);
		}

	REP(i, n) {
		REP(j, n) {
			if (dis[i][j] == Max) {

				queue<int> que;
				que.push(i);
				used[i] = 1;
				used[j] = 1;
				while (que.size()) {
					int cur = que.front();
					que.pop();

					if (cur == j || al[cur][j]) continue;
					al[cur][j] = 1;
					used[cur] = 1;

					for (auto itr : g.g[cur]) {
						if (dis[itr.first][j] == dis[cur][j] - itr.second && !al[itr.first][j]) {
							que.push(itr.first);
						}
					}

				}

			}
		}
	}

	int sum = 0;
	REP(i, n)
		sum += 1 - used[i];
	cout << sum << endl;
	REP(i, n)
		if (used[i] == 0) {
			printf("%d\n", i + 1);
		}
	return 0;
}

Measured memory_bytes: 12320