#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize ("O3")
#pragma GCC optimize ("O2")
#pragma GCC optimize ("O1")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#pragma GCC optimize ("fast-math")
#define ezurect int T; cin >> T; while(T--){solve();}
const int N = 1e3 + 1, M = 4e5 + 1, mod = 666013;

int n, m;
vector<int> liste[N];
vector<vector<int>> cost(N, vector<int>(N)), f(N, vector<int>(N)), mamata(N, vector<int>(N));
vector<int> p(N);
vector<int> viz(N);
vector<pair<int, int>> edges;
int bfs(){
    queue<int> q;
    q.push(1);
    p.assign(N, -1);
    p[1] = 0;

    while(!q.empty()){
        int nod = q.front();
        q.pop();
        if(nod == n){
            continue;
        }
        for(auto i : liste[nod]){
            if(p[i] == -1 && f[nod][i] < cost[nod][i]){
                p[i] = nod;
                q.push(i);
            }
        }
    }
    if(p[n] < 0) return 0;
    return 1;
}
int MaxFlow(){
    int maxflow = 0;
    while(bfs()){
        int t = n;
        for(auto i : liste[t]){
            if(f[i][t] == cost[i][t] || p[i] == -1){
                continue;
            }
            p[t] = i;
            int minim = 1e9;
            for(int j = t; j != 1; j = p[j]){
                minim = min(minim, cost[p[j]][j] - f[p[j]][j]);
            }
            for(int j = t; j != 1; j = p[j]){
                f[p[j]][j] += minim;
                f[j][p[j]] -= minim;
            }
            maxflow += minim;
        }
    }
    return maxflow;
}

void dfs(int nod){
    viz[nod] = 1;
    for(auto i : liste[nod]){
        if(viz[i] == 0 && f[nod][i] < cost[nod][i]){
            dfs(i);
        }
    }
}
void dfs1(int nod){
    viz[nod] = 1;
    for(auto i : liste[nod]){
        if(viz[i] == 0 && f[i][nod] < cost[i][nod]){
            dfs1(i);
        }
    }
}
int main(){
    ifstream fin("critice.in");
    ofstream fout("critice.out");
    fin.tie(0)->sync_with_stdio(0);
    fin >> n >> m;
    for(int i = 1; i <= m; i++){
        int u, v, c;
        fin >> u >> v >> c;
        liste[u].push_back(v);
        liste[v].push_back(u);
        cost[u][v] = c;
        cost[v][u] = c;
        mamata[u][v] = mamata[v][u] = i;
        edges.push_back({u, v});
    }

    int pula = MaxFlow();
    set<int> sol;
    
    for(auto i : liste[1]){
        if(f[1][i] == cost[1][i]){
            viz.assign(N, 0);
            viz[1] = 1;
            dfs(i);
            if(viz[n]){
                sol.insert(mamata[i][1]);
            }
        }
    }
    for(auto i : liste[n]){
        if(f[i][n] == cost[i][n]){
            viz.assign(n, 0);
            viz[n] = 1;
            dfs1(i);
            if(viz[1]){
                sol.insert(mamata[n][i]);
            }
        }
    }
    fout << sol.size() << '\n';
    for(auto i : sol){
        fout << i << '\n';
    }
}