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

const int INF = 2000000000;
int n, m, TT[1005];
int C[1005][1005], F[1005][1005];
bool f[1005];
vector <pair <int, int> > v[1005];
queue <int> q;
vector <int> Sol;
bool f1[1005], f2[1005];
struct muchie{
    int x, y, c;
};
muchie a[1005];
inline bool Bfs(){
    memset(f, 0, sizeof(f));
    q.push(1);
    f[1] = 1;
    while(!q.empty()){
        int nod = q.front();
        q.pop();
        if(nod == n) continue ;
        for(auto it : v[nod]){
            if(C[nod][it.first] == F[nod][it.first] || f[it.first]) continue ;
            q.push(it.first);
            f[it.first] = 1;
            TT[it.first] = nod;
        }
    }
    return f[n];
}
int main(){
    freopen("critice.in", "r", stdin);
    freopen("critice.out", "w", stdout);
    scanf("%d%d", &n, &m);
    int x, y, c;
    for(int i = 1; i <= m ; ++i){
        scanf("%d%d%d", &x, &y, &c);
        C[x][y] += c;
        C[y][x] += c;
        v[x].push_back({y, i});
        v[y].push_back({x, i});
    }
    while(Bfs()){
        for(auto it : v[n]){
            int nod = it.first;
            if(F[nod][n] == C[nod][n] || !f[nod]) continue ;
            TT[n] = nod;
            int fmin = INF;
            for(nod = n; nod != 1 ; nod = TT[nod])
                fmin = min(fmin, C[TT[nod]][nod] - F[TT[nod]][nod]);
            if(fmin == 0) continue ;
            for(nod = n; nod != 1 ; nod = TT[nod]){
                F[TT[nod]][nod] += fmin;
                F[nod][TT[nod]] -= fmin;
            }
        }
    }
    memset(f, 0, sizeof(f));
    q.push(1);
    while(!q.empty()){
        int nod = q.front();
        q.pop();
        for(auto it : v[nod]){
            if(f[it.second]) continue ;
            f[it.second] = 1;
            if(abs(F[nod][it.first]) == C[nod][it.first]) f1[it.second] = 1;
            else q.push(it.first);
        }
    }

    memset(f, 0, sizeof(f));
    q.push(n);
    while(!q.empty()){
        int nod = q.front();
        q.pop();
        for(auto it : v[nod]){
            if(f[it.second]) continue ;
            f[it.second] = 1;
            if(abs(F[nod][it.first]) == C[nod][it.first]) f2[it.second] = 1;
            else q.push(it.first);
        }
    }

    for(int i = 1; i <= n ; ++i)
        if(f1[i] == f2[i] && f2[i] == 1) Sol.push_back(i);

    printf("%d\n", Sol.size());
    for(auto it : Sol)
        printf("%d\n", it);
    return 0;
}